Patchwork [v10] i2c: exynos5: add High Speed I2C controller driver

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Submitter Naveen Krishna Ch
Date June 19, 2013, 10:48 a.m.
Message ID <1371638905-30633-1-git-send-email-ch.naveen@samsung.com>
Download mbox | patch
Permalink /patch/252553/
State Superseded
Headers show

Comments

Naveen Krishna Ch - June 19, 2013, 10:48 a.m.
Adds support for High Speed I2C driver found in Exynos5 and
later SoCs from Samsung.

Driver only supports Device Tree method.

Changes since v1:
1. Added FIFO functionality
2. Added High speed mode functionality
3. Remove SMBUS_QUICK
4. Remove the debugfs functionality
5. Use devm_* functions where ever possible
6. Driver is free from GPIO configs
7. Use OF data string "clock-frequency" to get the bus operating frequencies
8. Split the clock divisor calculation function
9. Add resets for the failed transacton cases
10. Removed retries as core does retries if -EAGAIN is returned
11. Removed mode from device tree info (use speed to distinguish
    the mode of operation)
12. Use wait_for_completion_timeout as the interruptible case is not tested well
13. few other bug fixes and cosmetic changes

Signed-off-by: Taekgyun Ko <taeggyun.ko@samsung.com>
Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Reviewed-by: Simon Glass <sjg@google.com>
Tested-by: Andrew Bresticker <abrestic@google.com>
Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
Signed-off-by: Andrew Bresticker <abrestic@google.com>
---

Changes since v9:
Fixed below comments given by Wolfram, Thanks for the reivew.
1. Removed retries as core does retries if -EAGAIN is returned
2. Removed mode from device tree info (use speed to distinguish
   the mode of operation)
3. Use module_platform_driver macro instead of init and exit
4. Use wait_for_completion_timeout as the interruptible case is not tested well

 .../devicetree/bindings/i2c/i2c-exynos5.txt        |   44 +
 drivers/i2c/busses/Kconfig                         |    7 +
 drivers/i2c/busses/Makefile                        |    1 +
 drivers/i2c/busses/i2c-exynos5.c                   |  861 ++++++++++++++++++++
 4 files changed, 913 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
 create mode 100644 drivers/i2c/busses/i2c-exynos5.c
Wolfram Sang - July 1, 2013, 6:17 a.m.
On Wed, Jun 19, 2013 at 04:18:25PM +0530, Naveen Krishna Chatradhi wrote:
> Adds support for High Speed I2C driver found in Exynos5 and
> later SoCs from Samsung.
> 
> Driver only supports Device Tree method.
> 
> Changes since v1:
> 1. Added FIFO functionality
> 2. Added High speed mode functionality
> 3. Remove SMBUS_QUICK
> 4. Remove the debugfs functionality
> 5. Use devm_* functions where ever possible
> 6. Driver is free from GPIO configs
> 7. Use OF data string "clock-frequency" to get the bus operating frequencies
> 8. Split the clock divisor calculation function
> 9. Add resets for the failed transacton cases
> 10. Removed retries as core does retries if -EAGAIN is returned
> 11. Removed mode from device tree info (use speed to distinguish
>     the mode of operation)
> 12. Use wait_for_completion_timeout as the interruptible case is not tested well
> 13. few other bug fixes and cosmetic changes
> 
> Signed-off-by: Taekgyun Ko <taeggyun.ko@samsung.com>
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> Reviewed-by: Simon Glass <sjg@google.com>
> Tested-by: Andrew Bresticker <abrestic@google.com>
> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
> Signed-off-by: Andrew Bresticker <abrestic@google.com>
> ---
> 
> +Optional properties:
> +  - clock-frequency: Desired operating frequency in Hz of the bus.
> +    -> If not specified, the default value is 100khz in fast-speed mode and
> +       1Mhz in high-speed mode.

? If not specified, the default is 100kHz. There is no way to get 1MHz,
or?

...

> +static int exynos5_i2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct exynos5_i2c *i2c;
> +	struct resource *mem;
> +	unsigned int op_clock;

My compiler says:

drivers/i2c/busses/i2c-exynos5.c: In function ‘exynos5_i2c_probe’:
drivers/i2c/busses/i2c-exynos5.c:687:5: warning: ‘op_clock’ may be used uninitialized in this function [-Wuninitialized]

so...

> +	int ret;
> +
> +	if (!np) {
> +		dev_err(&pdev->dev, "no device node\n");
> +		return -ENOENT;
> +	}
> +
> +	i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
> +	if (!i2c) {
> +		dev_err(&pdev->dev, "no memory for state\n");
> +		return -ENOMEM;
> +	}
> +
> +	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
> +		i2c->speed_mode = HSI2C_FAST_SPD;
> +		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
> +	}
> +
> +	if (op_clock >= HSI2C_HS_TX_CLOCK) {

... this should be 'else if'

> +		i2c->speed_mode = HSI2C_HIGH_SPD;
> +		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
> +		i2c->hs_clock = op_clock;
> +	} else {
> +		i2c->speed_mode = HSI2C_FAST_SPD;
> +		i2c->fs_clock = op_clock;
> +	}

...

> +	i2c->bus_id = of_alias_get_id(i2c->adap.dev.of_node, "hsi2c");

Huh, the core already gets an alias for you. Can't you use 'adap.nr'?

Rest looks good.

Thanks!
Tomasz Figa - July 1, 2013, 10:25 a.m.
Hi Naveen,

Looks mostly good, but see some comments inline.

On Wednesday 19 of June 2013 16:18:25 Naveen Krishna Chatradhi wrote:
> Adds support for High Speed I2C driver found in Exynos5 and
> later SoCs from Samsung.
> 
> Driver only supports Device Tree method.
> 
> Changes since v1:
> 1. Added FIFO functionality
> 2. Added High speed mode functionality
> 3. Remove SMBUS_QUICK
> 4. Remove the debugfs functionality
> 5. Use devm_* functions where ever possible
> 6. Driver is free from GPIO configs
> 7. Use OF data string "clock-frequency" to get the bus operating
> frequencies 8. Split the clock divisor calculation function
> 9. Add resets for the failed transacton cases
> 10. Removed retries as core does retries if -EAGAIN is returned
> 11. Removed mode from device tree info (use speed to distinguish
>     the mode of operation)
> 12. Use wait_for_completion_timeout as the interruptible case is not
> tested well 13. few other bug fixes and cosmetic changes
> 
> Signed-off-by: Taekgyun Ko <taeggyun.ko@samsung.com>
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
> Reviewed-by: Simon Glass <sjg@google.com>
> Tested-by: Andrew Bresticker <abrestic@google.com>
> Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
> Signed-off-by: Andrew Bresticker <abrestic@google.com>
> ---
> 
> Changes since v9:
> Fixed below comments given by Wolfram, Thanks for the reivew.
> 1. Removed retries as core does retries if -EAGAIN is returned
> 2. Removed mode from device tree info (use speed to distinguish
>    the mode of operation)
> 3. Use module_platform_driver macro instead of init and exit
> 4. Use wait_for_completion_timeout as the interruptible case is not
> tested well
> 
>  .../devicetree/bindings/i2c/i2c-exynos5.txt        |   44 +
>  drivers/i2c/busses/Kconfig                         |    7 +
>  drivers/i2c/busses/Makefile                        |    1 +
>  drivers/i2c/busses/i2c-exynos5.c                   |  861
> ++++++++++++++++++++ 4 files changed, 913 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> create mode 100644 drivers/i2c/busses/i2c-exynos5.c
> 
> diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt new file mode
> 100644
> index 0000000..805e018
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
> @@ -0,0 +1,44 @@
> +* Samsung's High Speed I2C controller
> +
> +The Samsung's High Speed I2C controller is used to interface with I2C
> devices +at various speeds ranging from 100khz to 3.4Mhz.
> +
> +Required properties:
> +  - compatible: value should be.
> +      -> "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.

IMHO this compatible value is too wide. You might end up with new Exynos 5 
SoC that has a high speed I2C controller as well, but slightly different, 
requiring some extra quirks.  Now exynos5 in compatible would suggest that 
it covers all Exynos 5 SoCs, but such SoC would require new one.

Basically, my suggestion is to use a compatible value with name of first SoC 
in which given IP appeared, as it is already done in most bindings.

> +  - reg: physical base address of the controller and length of memory
> mapped +    region.
> +  - interrupts: interrupt number to the cpu.
> +  - #address-cells: always 1 (for i2c addresses)
> +  - #size-cells: always 0
> +
> +  - Pinctrl:
> +    - pinctrl-0: Pin control group to be used for this controller.
> +    - pinctrl-names: Should contain only one value - "default".
> +
> +Optional properties:
> +  - clock-frequency: Desired operating frequency in Hz of the bus.
> +    -> If not specified, the default value is 100khz in fast-speed mode
> and +       1Mhz in high-speed mode.
> +    -> If specified, The bus operates in high-speed mode only if the
> +       clock-frequency is >= 1Mhz.
> +
> +Example:
> +
> +hsi2c@12ca0000 {
> +	compatible = "samsung,exynos5-hsi2c";
> +	reg = <0x12ca0000 0x100>;
> +	interrupts = <56>;
> +	clock-frequency = <100000>;
> +
> +	pinctrl-0 = <&i2c4_bus>;
> +	pinctrl-names = "default";
> +
> +	#address-cells = <1>;
> +	#size-cells = <0>;
> +
> +	s2mps11_pmic@66 {
> +		compatible = "samsung,s2mps11-pmic";
> +		reg = <0x66>;
> +	};
> +};
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 96c6d82..fecbe66 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -434,6 +434,13 @@ config I2C_EG20T
>  	  ML7213/ML7223/ML7831 is companion chip for Intel Atom E6xx series.
>  	  ML7213/ML7223/ML7831 is completely compatible for Intel EG20T PCH.
> 
> +config I2C_EXYNOS5
> +	tristate "Exynos5 high-speed I2C driver"
> +	depends on ARCH_EXYNOS5 && OF
> +	help
> +	  Say Y here to include support for high-speed I2C controller in the
> +	  Exynos5 based Samsung SoCs.
> +
>  config I2C_GPIO
>  	tristate "GPIO-based bitbanging I2C"
>  	depends on GPIOLIB
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 385f99d..af6fa37 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -42,6 +42,7 @@ i2c-designware-platform-objs :=
> i2c-designware-platdrv.o obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+=
> i2c-designware-pci.o
>  i2c-designware-pci-objs := i2c-designware-pcidrv.o
>  obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
> +obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
>  obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
>  obj-$(CONFIG_I2C_HIGHLANDER)	+= i2c-highlander.o
>  obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
> diff --git a/drivers/i2c/busses/i2c-exynos5.c
> b/drivers/i2c/busses/i2c-exynos5.c new file mode 100644
> index 0000000..696d16f
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-exynos5.c
> @@ -0,0 +1,861 @@
> +/**
> + * i2c-exynos5.c - Samsung Exynos5 I2C Controller Driver
> + *
> + * Copyright (C) 2013 Samsung Electronics Co., Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> +*/
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/time.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/clk.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of_i2c.h>
> +
> +/*
> + * HSI2C controller from Samsung supports 2 modes of operation
> + * 1. Auto mode: Where in master automatically controls the whole
> transaction + * 2. Manual mode: Software controls the transaction by
> issuing commands + *    START, READ, WRITE, STOP, RESTART in
> I2C_MANUAL_CMD register. + *
> + * Operation mode can be selected by setting AUTO_MODE bit in I2C_CONF
> register + *

I think a comment about mode used in this driver would be good.

> + * Special bits are available for both modes of operation to set
> commands + * and for checking transfer status
> + */
> +
> +/* Register Map */
> +#define HSI2C_CTL		0x00
> +#define HSI2C_FIFO_CTL		0x04
> +#define HSI2C_TRAILIG_CTL	0x08
> +#define HSI2C_CLK_CTL		0x0C
> +#define HSI2C_CLK_SLOT		0x10
> +#define HSI2C_INT_ENABLE	0x20
> +#define HSI2C_INT_STATUS	0x24
> +#define HSI2C_ERR_STATUS	0x2C
> +#define HSI2C_FIFO_STATUS	0x30
> +#define HSI2C_TX_DATA		0x34
> +#define HSI2C_RX_DATA		0x38
> +#define HSI2C_CONF		0x40
> +#define HSI2C_AUTO_CONF		0x44
> +#define HSI2C_TIMEOUT		0x48
> +#define HSI2C_MANUAL_CMD	0x4C
> +#define HSI2C_TRANS_STATUS	0x50
> +#define HSI2C_TIMING_HS1	0x54
> +#define HSI2C_TIMING_HS2	0x58
> +#define HSI2C_TIMING_HS3	0x5C
> +#define HSI2C_TIMING_FS1	0x60
> +#define HSI2C_TIMING_FS2	0x64
> +#define HSI2C_TIMING_FS3	0x68
> +#define HSI2C_TIMING_SLA	0x6C
> +#define HSI2C_ADDR		0x70

nit: AFAIK lower case characters are preferred in hexadecimal numbers in 
kernel coding style.

> +/* I2C_CTL Register bits */
> +#define HSI2C_FUNC_MODE_I2C			(1u << 0)
> +#define HSI2C_MASTER				(1u << 3)
> +#define HSI2C_RXCHON				(1u << 6)
> +#define HSI2C_TXCHON				(1u << 7)
> +#define HSI2C_SW_RST				(1u << 31)
> +
> +/* I2C_FIFO_CTL Register bits */
> +#define HSI2C_RXFIFO_EN				(1u << 0)
> +#define HSI2C_TXFIFO_EN				(1u << 1)
> +#define HSI2C_FIFO_MAX				(0x40)

nit: You don't need parentheses in case of simple numbers.

> +#define HSI2C_RXFIFO_TRIGGER_LEVEL(x)		((x) << 4)
> +#define HSI2C_TXFIFO_TRIGGER_LEVEL(x)		((x) << 16)
> +/* I2C_TRAILING_CTL Register bits */
> +#define HSI2C_TRAILING_COUNT			(0xf)
> +
> +/* I2C_INT_EN Register bits */
> +#define HSI2C_INT_TX_ALMOSTEMPTY_EN		(1u << 0)
> +#define HSI2C_INT_RX_ALMOSTFULL_EN		(1u << 1)
> +#define HSI2C_INT_TRAILING_EN			(1u << 6)
> +#define HSI2C_INT_I2C_EN			(1u << 9)
> +
> +/* I2C_INT_STAT Register bits */
> +#define HSI2C_INT_TX_ALMOSTEMPTY		(1u << 0)
> +#define HSI2C_INT_RX_ALMOSTFULL			(1u << 1)
> +#define HSI2C_INT_TX_UNDERRUN			(1u << 2)
> +#define HSI2C_INT_TX_OVERRUN			(1u << 3)
> +#define HSI2C_INT_RX_UNDERRUN			(1u << 4)
> +#define HSI2C_INT_RX_OVERRUN			(1u << 5)
> +#define HSI2C_INT_TRAILING			(1u << 6)
> +#define HSI2C_INT_I2C				(1u << 9)
> +#define HSI2C_RX_INT				(HSI2C_INT_RX_ALMOSTFULL | \
> +						 HSI2C_INT_RX_UNDERRUN | \
> +						 HSI2C_INT_RX_OVERRUN | \
> +						 HSI2C_INT_TRAILING)
> +
> +/* I2C_FIFO_STAT Register bits */
> +#define HSI2C_RX_FIFO_EMPTY			(1u << 24)
> +#define HSI2C_RX_FIFO_FULL			(1u << 23)
> +#define HSI2C_RX_FIFO_LVL(x)			((x >> 16) & 0x7f)
> +#define HSI2C_TX_FIFO_EMPTY			(1u << 8)
> +#define HSI2C_TX_FIFO_FULL			(1u << 7)
> +#define HSI2C_TX_FIFO_LVL(x)			((x >> 0) & 0x7f)
> +#define HSI2C_FIFO_EMPTY			(HSI2C_RX_FIFO_EMPTY |	\
> +						HSI2C_TX_FIFO_EMPTY)
> +
> +/* I2C_CONF Register bits */
> +#define HSI2C_AUTO_MODE				(1u << 31)
> +#define HSI2C_10BIT_ADDR_MODE			(1u << 30)
> +#define HSI2C_HS_MODE				(1u << 29)
> +
> +/* I2C_AUTO_CONF Register bits */
> +#define HSI2C_READ_WRITE			(1u << 16)
> +#define HSI2C_STOP_AFTER_TRANS			(1u << 17)
> +#define HSI2C_MASTER_RUN			(1u << 31)
> +
> +/* I2C_TIMEOUT Register bits */
> +#define HSI2C_TIMEOUT_EN			(1u << 31)
> +
> +/* I2C_TRANS_STATUS register bits */
> +#define HSI2C_MASTER_BUSY			(1u << 17)
> +#define HSI2C_SLAVE_BUSY			(1u << 16)
> +#define HSI2C_TIMEOUT_AUTO			(1u << 4)
> +#define HSI2C_NO_DEV				(1u << 3)
> +#define HSI2C_NO_DEV_ACK			(1u << 2)
> +#define HSI2C_TRANS_ABORT			(1u << 1)
> +#define HSI2C_TRANS_DONE			(1u << 0)
> +
> +/* I2C_ADDR register bits */
> +#define HSI2C_SLV_ADDR_SLV(x)			((x & 0x3ff) << 0)
> +#define HSI2C_SLV_ADDR_MAS(x)			((x & 0x3ff) << 10)
> +#define HSI2C_MASTER_ID(x)			((x & 0xff) << 24)
> +#define MASTER_ID(x)				((x & 0x7) + 0x08)
> +
> +/*
> + * Controller operating frequency, timing values for operation
> + * are calculated against this frequency
> + */
> +#define HSI2C_HS_TX_CLOCK	1000000
> +#define HSI2C_FS_TX_CLOCK	100000
> +#define HSI2C_HIGH_SPD		1
> +#define HSI2C_FAST_SPD		0
> +
> +#define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(1000))
> +
> +/* timeout for pm runtime autosuspend */
> +#define EXYNOS5_I2C_PM_TIMEOUT		1000	/* ms */

1 second seems a lot, but I guess such block don't use too much power.

> +struct exynos5_i2c {
> +	struct i2c_adapter	adap;
> +	unsigned int		suspended:1;
> +
> +	struct i2c_msg		*msg;
> +	struct completion	msg_complete;
> +	unsigned int		msg_ptr;
> +	unsigned int		msg_len;
> +
> +	unsigned int		irq;
> +
> +	void __iomem		*regs;
> +	struct clk		*clk;
> +	struct device		*dev;
> +	int			state;
> +
> +	/*
> +	 * Since the TRANS_DONE bit is cleared on read, and we may read it
> +	 * either during an IRQ or after a transaction, keep track of its
> +	 * state here.
> +	 */
> +	int			trans_done;
> +
> +	/* Controller operating frequency */
> +	unsigned int		fs_clock;
> +	unsigned int		hs_clock;
> +
> +	/*
> +	 * HSI2C Controller can operate in
> +	 * 1. High speed upto 3.4Mbps
> +	 * 2. Fast speed upto 1Mbps
> +	 */
> +	int			speed_mode;
> +	int			bus_id;
> +};
> +
> +static const struct of_device_id exynos5_i2c_match[] = {
> +	{ .compatible = "samsung,exynos5-hsi2c" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, exynos5_i2c_match);
> +
> +static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c)
> +{
> +	writel(readl(i2c->regs + HSI2C_INT_STATUS),
> +				i2c->regs + HSI2C_INT_STATUS);
> +}
> +
> +/*
> + * exynos5_i2c_set_timing: updates the registers with appropriate
> + * timing values calculated
> + *
> + * Returns 0 on success, -EINVAL if the cycle length cannot
> + * be calculated.
> + */
> +static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
> +{
> +	u32 i2c_timing_s1;
> +	u32 i2c_timing_s2;
> +	u32 i2c_timing_s3;
> +	u32 i2c_timing_sla;
> +	unsigned int t_start_su, t_start_hd;
> +	unsigned int t_stop_su;
> +	unsigned int t_data_su, t_data_hd;
> +	unsigned int t_scl_l, t_scl_h;
> +	unsigned int t_sr_release;
> +	unsigned int t_ftl_cycle;
> +	unsigned int clkin = clk_get_rate(i2c->clk);
> +	unsigned int div, utemp0 = 0, utemp1 = 0, clk_cycle;
> +	unsigned int op_clk = (mode == HSI2C_HIGH_SPD) ?
> +				i2c->hs_clock : i2c->fs_clock;
> +
> +	/*
> +	 * FPCLK / FI2C =
> +	 * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
> +	 * utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
> +	 * utemp1 = (TSCLK_L + TSCLK_H + 2)
> +	 */
> +	t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
> +	utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;
> +
> +	/* CLK_DIV max is 256 */
> +	for (div = 0; div < 256; div++) {
> +		utemp1 = utemp0 / (div + 1);
> +
> +		/*
> +		 * SCL_L and SCL_H each has max value of 255
> +		 * Hence, For the clk_cycle to the have right value
> +		 * utemp1 has to be less then 512 and more than 4.
> +		 */
> +		if ((utemp1 < 512) && (utemp1 > 4)) {
> +			clk_cycle = utemp1 - 2;
> +			break;
> +		} else if (div == 255) {
> +			dev_warn(i2c->dev, "Failed to calculate divisor");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	t_scl_l = clk_cycle / 2;
> +	t_scl_h = clk_cycle / 2;
> +	t_start_su = t_scl_l;
> +	t_start_hd = t_scl_l;
> +	t_stop_su = t_scl_l;
> +	t_data_su = t_scl_l / 2;
> +	t_data_hd = t_scl_l / 2;
> +	t_sr_release = clk_cycle;
> +
> +	i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
> +	i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
> +	i2c_timing_s3 = div << 16 | t_sr_release << 0;
> +	i2c_timing_sla = t_data_hd << 0;
> +
> +	dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
> +		t_start_su, t_start_hd, t_stop_su);
> +	dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
> +		t_data_su, t_scl_l, t_scl_h);
> +	dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
> +		div, t_sr_release);
> +	dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);
> +
> +	if (mode == HSI2C_HIGH_SPD) {
> +		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
> +		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
> +		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
> +	} else {
> +		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
> +		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
> +		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
> +	}
> +	writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);
> +
> +	return 0;
> +}
> +
> +static int exynos5_hsi2c_clock_setup(struct exynos5_i2c *i2c)
> +{
> +	/*
> +	 * Configure the Fast speed timing values
> +	 * Even the High Speed mode initially starts with Fast mode
> +	 */
> +	if (exynos5_i2c_set_timing(i2c, HSI2C_FAST_SPD)) {
> +		dev_err(i2c->dev, "HSI2C FS Clock set up failed\n");
> +		return -EINVAL;
> +	}
> +
> +	/* configure the High speed timing values */
> +	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
> +		if (exynos5_i2c_set_timing(i2c, HSI2C_HIGH_SPD)) {
> +			dev_err(i2c->dev, "HSI2C HS Clock set up failed\n");
> +			return -EINVAL;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * exynos5_i2c_init: configures the controller for I2C functionality
> + * Programs I2C controller for Master mode operation
> + */
> +static void exynos5_i2c_init(struct exynos5_i2c *i2c)
> +{
> +	u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
> +
> +	writel((HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
> +					i2c->regs + HSI2C_CTL);
> +	writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);
> +
> +	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
> +		writel(HSI2C_MASTER_ID(MASTER_ID(i2c->bus_id)),
> +					i2c->regs + HSI2C_ADDR);
> +		i2c_conf |= HSI2C_HS_MODE;
> +	}
> +
> +	writel(i2c_conf | HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
> +}
> +
> +static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
> +{
> +	u32 i2c_ctl;
> +
> +	/* Set and clear the bit for reset */
> +	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
> +	i2c_ctl |= HSI2C_SW_RST;
> +	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
> +
> +	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
> +	i2c_ctl &= ~HSI2C_SW_RST;
> +	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
> +
> +	/* We don't expect calculations to fail during the run */
> +	exynos5_hsi2c_clock_setup(i2c);
> +	/* Initialize the configure registers */
> +	exynos5_i2c_init(i2c);
> +}
> +
> +/*
> + * exynos5_i2c_irq: top level IRQ servicing routine
> + *
> + * INT_STATUS registers gives the interrupt details. Further,
> + * FIFO_STATUS or TRANS_STATUS registers are to be check for detailed
> + * state of the bus.
> + */
> +static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
> +{
> +	struct exynos5_i2c *i2c = dev_id;
> +	u32 fifo_level, int_status, fifo_status, trans_status;
> +	unsigned char byte;
> +	int len = 0;
> +
> +	i2c->state = -EINVAL;
> +
> +	int_status = readl(i2c->regs + HSI2C_INT_STATUS);
> +	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
> +
> +	if (int_status & HSI2C_INT_I2C) {
> +		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
> +		if (trans_status & HSI2C_NO_DEV_ACK) {
> +			dev_dbg(i2c->dev, "No ACK from device\n");
> +			i2c->state = -ENXIO;
> +		} else if (trans_status & HSI2C_NO_DEV) {
> +			dev_dbg(i2c->dev, "No device\n");
> +			i2c->state = -ENXIO;
> +		} else if (trans_status & HSI2C_TRANS_ABORT) {
> +			dev_dbg(i2c->dev, "Deal with arbitration lose\n");
> +			i2c->state = -EAGAIN;
> +		} else if (trans_status & HSI2C_TIMEOUT_AUTO) {
> +			dev_dbg(i2c->dev, "Accessing device timed out\n");
> +			i2c->state = -EAGAIN;
> +		} else if (trans_status & HSI2C_TRANS_DONE) {
> +			i2c->trans_done = 1;
> +			i2c->state = 0;
> +		}
> +	}
> +	/* TX_ALMOSTEMPTY can happen along with HSI2C_INT_I2C */

The comment says that both can happen, while your code assumes they are 
exlusive.

> +	else if (int_status &
> +			(HSI2C_INT_TX_UNDERRUN | HSI2C_INT_TX_ALMOSTEMPTY)) {
> +		fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);
> +
> +		/* To support probing the devices for detection */
> +		if (i2c->msg->len == 0) {
> +			i2c->state = -ENXIO;
> +			goto stop;
> +		}
> +
> +		len = HSI2C_FIFO_MAX - fifo_level;
> +		if (len > i2c->msg->len)
> +			len = i2c->msg->len;
> +
> +		i2c->msg_len += len;
> +		while (len > 0) {
> +			byte = i2c->msg->buf[i2c->msg_ptr++];
> +			writel(byte, i2c->regs + HSI2C_TX_DATA);
> +			len--;
> +		}
> +		i2c->state = 0;
> +		goto stop;
> +	}
> +	/* If TX FIFO is full (give chance to clear) */
> +	else if (int_status & HSI2C_INT_TX_OVERRUN)

Is this even possible? The only reason for TX overrun I can see would be 
the driver trying to put data in FIFO when it doesn't have enough space, 
which shouldn't happen.

> +		i2c->state = 0;
> +
> +	if (int_status & (HSI2C_INT_RX_OVERRUN | HSI2C_INT_TRAILING |
> +		HSI2C_INT_RX_UNDERRUN | HSI2C_INT_RX_ALMOSTFULL)) {
> +		fifo_level = HSI2C_RX_FIFO_LVL(fifo_status);
> +
> +		if (fifo_level >= i2c->msg->len)
> +			len = i2c->msg->len;
> +		else
> +			len = fifo_level;
> +
> +		i2c->msg_len += len;
> +		while (len > 0) {
> +			byte = (unsigned char)
> +				readl(i2c->regs + HSI2C_RX_DATA);
> +			i2c->msg->buf[i2c->msg_ptr++] = byte;
> +			len--;
> +		}
> +		i2c->state = 0;
> +	}
> +
> +
> + stop:
> +	if ((i2c->msg_len == i2c->msg->len) || (i2c->state < 0)) {
> +		writel(0, i2c->regs + HSI2C_INT_ENABLE);
> +		complete(&i2c->msg_complete);
> +	}
> +
> +	exynos5_i2c_clr_pend_irq(i2c);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +/*
> + * exynos5_i2c_wait_bus_idle
> + *
> + * Wait for the transaction to complete (indicated by the TRANS_DONE bit
> + * being set), and, if this is the last message in a transfer, wait for
> the + * MASTER_BUSY bit to be cleared.
> + *
> + * Returns -EBUSY if the bus cannot be brought to idle
> + */
> +static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c, int stop)
> +{
> +	unsigned long stop_time;
> +	u32 trans_status;
> +
> +	/* wait for 100 milli seconds for the bus to be idle */
> +	stop_time = jiffies + msecs_to_jiffies(100) + 1;
> +	do {
> +		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
> +		if (trans_status & HSI2C_TRANS_DONE)
> +			i2c->trans_done = 1;
> +		/*
> +		 * Only wait for MASTER_BUSY to be cleared if this is the last
> +		 * message.
> +		 */
> +		if ((!stop || !(trans_status & HSI2C_MASTER_BUSY)) &&
> +		    i2c->trans_done)
> +			return 0;
> +
> +		usleep_range(50, 200);
> +	} while (time_before(jiffies, stop_time));
> +
> +	return -EBUSY;
> +}
> +
> +/*
> + * exynos5_i2c_message_start: Configures the bus and starts the xfer
> + * i2c: struct exynos5_i2c pointer for the current bus
> + * stop: Enables stop after transfer if set. Set for last transfer of
> + *       in the list of messages.
> + *
> + * Configures the bus for read/write function
> + * Sets chip address to talk to, message length to be sent.
> + * Enables appropriate interrupts and sends start xfer command.
> + */
> +static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
> +{
> +	u32 i2c_ctl;
> +	u32 int_en = HSI2C_INT_I2C_EN;
> +	u32 i2c_auto_conf = 0;
> +	u32 fifo_ctl;
> +	u32 i2c_timeout;
> +
> +	/*
> +	 * When the message length is > FIFO depth, set the FIFO trigger
> +	 * at FIFO_MAX - 4. Just for ease of handling.
> +	 */
> +	unsigned short len = (i2c->msg->len > HSI2C_FIFO_MAX) ?
> +					(HSI2C_FIFO_MAX - 4) : i2c->msg->len;
> +
> +	/* Clear to enable Timeout */
> +	i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);
> +	i2c_timeout &= ~HSI2C_TIMEOUT_EN;
> +	writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);
> +
> +	fifo_ctl = HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN;
> +	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
> +
> +	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
> +	i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
> +	if (i2c->msg->flags & I2C_M_RD) {
> +		i2c_ctl |= HSI2C_RXCHON;
> +
> +		i2c_auto_conf |= HSI2C_READ_WRITE;
> +
> +		fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(len);
> +		int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
> +			HSI2C_INT_TRAILING_EN);
> +	} else {
> +		i2c_ctl |= HSI2C_TXCHON;
> +
> +		fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(len);
> +		int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
> +	}
> +
> +	if (stop == 1)
> +		i2c_auto_conf |= HSI2C_STOP_AFTER_TRANS;
> +
> +	writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);
> +
> +	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
> +	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
> +
> +	/* In auto mode the length of xfer cannot be 0 */
> +	if (i2c->msg->len == 0)
> +		i2c_auto_conf |= 0x1;
> +	else
> +		i2c_auto_conf |= i2c->msg->len;
> +
> +	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
> +
> +	/* Start data transfer in Master mode */
> +	i2c_auto_conf = readl(i2c->regs + HSI2C_AUTO_CONF);
> +	i2c_auto_conf |= HSI2C_MASTER_RUN;
> +	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
> +
> +	writel(int_en, i2c->regs + HSI2C_INT_ENABLE);
> +}
> +
> +static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
> +			      struct i2c_msg *msgs, int stop)
> +{
> +	unsigned long timeout;
> +	int ret;
> +
> +	i2c->msg = msgs;
> +	i2c->msg_ptr = 0;
> +	i2c->msg_len = 0;
> +	i2c->trans_done = 0;
> +
> +	INIT_COMPLETION(i2c->msg_complete);
> +
> +	exynos5_i2c_message_start(i2c, stop);
> +
> +	timeout = wait_for_completion_timeout
> +		(&i2c->msg_complete, EXYNOS5_I2C_TIMEOUT);
> +	if (timeout == 0) {
> +		exynos5_i2c_reset(i2c);
> +		dev_warn(i2c->dev, "%s timeout\n",
> +			 (msgs->flags & I2C_M_RD) ? "rx" : "tx");
> +		return timeout;
> +	}
> +
> +	ret = i2c->state;
> +
> +	if (ret == -EAGAIN) {
> +		exynos5_i2c_reset(i2c);
> +		return ret;
> +	}
> +
> +	/*
> +	 * If this is the last message to be transfered (stop == 1)
> +	 * Then check if the bus can be brought back to idle.
> +	 *
> +	 * Return -EBUSY if the bus still busy.
> +	 */
> +	if (exynos5_i2c_wait_bus_idle(i2c, stop))
> +		return -EBUSY;
> +
> +	/* Return the state as in interrupt routine */
> +	return ret;
> +}
> +
> +static int exynos5_i2c_xfer(struct i2c_adapter *adap,
> +			struct i2c_msg *msgs, int num)
> +{
> +	struct exynos5_i2c *i2c = (struct exynos5_i2c *)adap->algo_data;
> +	struct i2c_msg *msgs_ptr = msgs;
> +	int i = 0;
> +	int ret = 0, ret_pm;
> +	int stop = 0;
> +
> +	if (i2c->suspended) {
> +		dev_err(i2c->dev, "HS-I2C is not initialzed.\n");
> +		return -EIO;
> +	}
> +
> +	ret_pm = pm_runtime_get_sync(i2c->dev);
> +	if (IS_ERR_VALUE(ret_pm)) {

This looks wrong to me.

#define MAX_ERRNO       4095
#define IS_ERR_VALUE(x) unlikely((x) >= (unsigned long)-MAX_ERRNO)

This makes it:

if (unlikely((ret_pm) >= 0xFFFFF001)

which is obviously impossible for a signed value, such as ret_pm, which can 
be at most 0x7FFFFFFF.

Just check for ret_pm < 0 here and in other occurencies of IS_ERR_VALUE() 
in this driver.

> +		ret = -EIO;
> +		goto out;
> +	}
> +
> +	clk_prepare_enable(i2c->clk);

Shouldn't this (and any other clock gating/ungating) be inside a runtime PM 
callback? (Also this driver enables runtime PM, but lacks any callbacks. Is 
it really correct?)

> +
> +	for (i = 0; i < num; i++) {
> +		stop = (i == num - 1);
> +
> +		ret = exynos5_i2c_xfer_msg(i2c, msgs_ptr, stop);
> +		msgs_ptr++;
> +
> +		if (ret < 0)
> +			goto out;
> +	}
> +
> +	if (i == num) {
> +		ret = num;
> +	} else {
> +		/* Only one message, cannot access the device */
> +		if (i == 1)
> +			ret = -EREMOTEIO;
> +		else
> +			ret = i;
> +
> +		dev_warn(i2c->dev, "xfer message failed\n");
> +	}
> +
> + out:
> +	clk_disable_unprepare(i2c->clk);
> +	pm_runtime_mark_last_busy(i2c->dev);
> +	pm_runtime_put_autosuspend(i2c->dev);
> +	return ret;
> +}
> +
> +static u32 exynos5_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> +}
> +
> +static const struct i2c_algorithm exynos5_i2c_algorithm = {
> +	.master_xfer		= exynos5_i2c_xfer,
> +	.functionality		= exynos5_i2c_func,
> +};
> +
> +static int exynos5_i2c_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct exynos5_i2c *i2c;
> +	struct resource *mem;
> +	unsigned int op_clock;
> +	int ret;
> +
> +	if (!np) {
> +		dev_err(&pdev->dev, "no device node\n");
> +		return -ENOENT;
> +	}
> +
> +	i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
> +	if (!i2c) {
> +		dev_err(&pdev->dev, "no memory for state\n");
> +		return -ENOMEM;
> +	}
> +
> +	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
> +		i2c->speed_mode = HSI2C_FAST_SPD;
> +		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
> +	}
> +
> +	if (op_clock >= HSI2C_HS_TX_CLOCK) {
> +		i2c->speed_mode = HSI2C_HIGH_SPD;
> +		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
> +		i2c->hs_clock = op_clock;
> +	} else {
> +		i2c->speed_mode = HSI2C_FAST_SPD;
> +		i2c->fs_clock = op_clock;
> +	}
> +
> +	strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
> +	i2c->adap.owner   = THIS_MODULE;
> +	i2c->adap.algo    = &exynos5_i2c_algorithm;
> +	i2c->adap.retries = 2;
> +
> +	i2c->dev = &pdev->dev;
> +	i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
> +	if (IS_ERR(i2c->clk)) {
> +		dev_err(&pdev->dev, "cannot get clock\n");
> +		return -ENOENT;
> +	}
> +
> +	clk_prepare_enable(i2c->clk);
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
> +	if (IS_ERR(i2c->regs)) {
> +		ret = PTR_ERR(i2c->regs);
> +		goto err_clk;
> +	}
> +
> +	i2c->adap.dev.of_node = np;
> +	i2c->adap.algo_data = i2c;
> +	i2c->adap.dev.parent = &pdev->dev;
> +
> +	/* Clear pending interrupts from u-boot or misc causes */
> +	exynos5_i2c_clr_pend_irq(i2c);
> +
> +	init_completion(&i2c->msg_complete);
> +
> +	i2c->irq = ret = irq_of_parse_and_map(np, 0);
> +	if (ret <= 0) {
> +		dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
> +		ret = -EINVAL;
> +		goto err_clk;
> +	}

Please use platform_get_irq(pdev, 0) here. Don't waste the effort that is 
put into creating all those resources by of_platform_populate() early in 
boot process.

> +
> +	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
> +				0, dev_name(&pdev->dev), i2c);
> +
> +	if (ret != 0) {
> +		dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
> +		goto err_clk;
> +	}
> +
> +	/*
> +	 * TODO: Use private lock to avoid race conditions as
> +	 * mentioned in pm_runtime.txt
> +	 */
> +	pm_runtime_enable(i2c->dev);
> +	pm_runtime_set_autosuspend_delay(i2c->dev, EXYNOS5_I2C_PM_TIMEOUT);
> +	pm_runtime_use_autosuspend(i2c->dev);
> +
> +	ret = pm_runtime_get_sync(i2c->dev);
> +	if (IS_ERR_VALUE(ret))
> +		goto err_clk;
> +
> +	ret = exynos5_hsi2c_clock_setup(i2c);
> +	if (ret)
> +		goto err_pm;
> +
> +	i2c->bus_id = of_alias_get_id(i2c->adap.dev.of_node, "hsi2c");

AFAIK it's responsibility of i2c core to handle this.

> +
> +	exynos5_i2c_init(i2c);
> +
> +	ret = i2c_add_adapter(&i2c->adap);

You can call i2c_add_numbered_adapter() here to make i2c core assign a 
number to your adapter, either automatically or using device tree alias.

Best regards,
Tomasz

> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
> +		goto err_pm;
> +	}
> +
> +	of_i2c_register_devices(&i2c->adap);
> +	platform_set_drvdata(pdev, i2c);
> +
> +	clk_disable_unprepare(i2c->clk);
> +	pm_runtime_mark_last_busy(i2c->dev);
> +	pm_runtime_put_autosuspend(i2c->dev);
> +
> +	return 0;
> +
> + err_pm:
> +	pm_runtime_put(i2c->dev);
> +	pm_runtime_disable(&pdev->dev);
> + err_clk:
> +	clk_disable_unprepare(i2c->clk);
> +	return ret;
> +}
> +
> +static int exynos5_i2c_remove(struct platform_device *pdev)
> +{
> +	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	ret = pm_runtime_get_sync(&pdev->dev);
> +	if (IS_ERR_VALUE(ret))
> +		return ret;
> +
> +	i2c_del_adapter(&i2c->adap);
> +
> +	pm_runtime_put(&pdev->dev);
> +	pm_runtime_disable(&pdev->dev);
> +
> +	clk_disable_unprepare(i2c->clk);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int exynos5_i2c_suspend_noirq(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
> +
> +	i2c->suspended = 1;
> +
> +	return 0;
> +}
> +
> +static int exynos5_i2c_resume_noirq(struct device *dev)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
> +	int ret = 0;
> +
> +	clk_prepare_enable(i2c->clk);
> +
> +	ret = exynos5_hsi2c_clock_setup(i2c);
> +	if (ret) {
> +		clk_disable_unprepare(i2c->clk);
> +		return ret;
> +	}
> +
> +	exynos5_i2c_init(i2c);
> +	clk_disable_unprepare(i2c->clk);
> +	i2c->suspended = 0;
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops exynos5_i2c_dev_pm_ops = {
> +	.suspend_noirq = exynos5_i2c_suspend_noirq,
> +	.resume_noirq	= exynos5_i2c_resume_noirq,
> +};
> +
> +#define EXYNOS5_DEV_PM_OPS (&exynos5_i2c_dev_pm_ops)
> +#else
> +#define EXYNOS5_DEV_PM_OPS NULL
> +#endif
> +
> +static struct platform_driver exynos5_i2c_driver = {
> +	.probe		= exynos5_i2c_probe,
> +	.remove		= exynos5_i2c_remove,
> +	.driver		= {
> +		.owner	= THIS_MODULE,
> +		.name	= "exynos5-hsi2c",
> +		.pm	= EXYNOS5_DEV_PM_OPS,
> +		.of_match_table = exynos5_i2c_match,
> +	},
> +};
> +
> +module_platform_driver(exynos5_i2c_driver);
> +
> +MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
> +MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen@samsung.com>");
> +MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko@samsung.com>");
> +MODULE_LICENSE("GPL v2");
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Wolfram Sang - Aug. 15, 2013, 1:12 p.m.
On Mon, Jul 01, 2013 at 12:25:19PM +0200, Tomasz Figa wrote:
> Hi Naveen,
> 
> Looks mostly good, but see some comments inline.

Ping?
naveen krishna chatradhi - Aug. 16, 2013, 4:58 a.m.
On 15 August 2013 18:42, Wolfram Sang <wsa@the-dreams.de> wrote:
> On Mon, Jul 01, 2013 at 12:25:19PM +0200, Tomasz Figa wrote:
>> Hi Naveen,
>>
>> Looks mostly good, but see some comments inline.
>
> Ping?
Hello Wolfram,

I made a patch fixing your comments and from Thomas Figa as well.

Meanwhile, we hit a random crash in exynos5_i2c_irq function.
The "len" variable being is still being near the FIFO_MAX after this condition
 len = HSI2C_FIFO_MAX - fifo_level;
 +             if (len > i2c->msg->len)
 +                     len = i2c->msg->len;

Once, we fix this problem. i planned to rebase and submit.

Is it okey with you?

Thanks,
Naveen
>
Wolfram Sang - Aug. 16, 2013, 7:05 a.m.
> Once, we fix this problem. i planned to rebase and submit.
> 
> Is it okey with you?

Perfectly fine. Thanks for the heads up.

Patch

diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
new file mode 100644
index 0000000..805e018
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
@@ -0,0 +1,44 @@ 
+* Samsung's High Speed I2C controller
+
+The Samsung's High Speed I2C controller is used to interface with I2C devices
+at various speeds ranging from 100khz to 3.4Mhz.
+
+Required properties:
+  - compatible: value should be.
+      -> "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.
+  - reg: physical base address of the controller and length of memory mapped
+    region.
+  - interrupts: interrupt number to the cpu.
+  - #address-cells: always 1 (for i2c addresses)
+  - #size-cells: always 0
+
+  - Pinctrl:
+    - pinctrl-0: Pin control group to be used for this controller.
+    - pinctrl-names: Should contain only one value - "default".
+
+Optional properties:
+  - clock-frequency: Desired operating frequency in Hz of the bus.
+    -> If not specified, the default value is 100khz in fast-speed mode and
+       1Mhz in high-speed mode.
+    -> If specified, The bus operates in high-speed mode only if the
+       clock-frequency is >= 1Mhz.
+
+Example:
+
+hsi2c@12ca0000 {
+	compatible = "samsung,exynos5-hsi2c";
+	reg = <0x12ca0000 0x100>;
+	interrupts = <56>;
+	clock-frequency = <100000>;
+
+	pinctrl-0 = <&i2c4_bus>;
+	pinctrl-names = "default";
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+
+	s2mps11_pmic@66 {
+		compatible = "samsung,s2mps11-pmic";
+		reg = <0x66>;
+	};
+};
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 96c6d82..fecbe66 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -434,6 +434,13 @@  config I2C_EG20T
 	  ML7213/ML7223/ML7831 is companion chip for Intel Atom E6xx series.
 	  ML7213/ML7223/ML7831 is completely compatible for Intel EG20T PCH.
 
+config I2C_EXYNOS5
+	tristate "Exynos5 high-speed I2C driver"
+	depends on ARCH_EXYNOS5 && OF
+	help
+	  Say Y here to include support for high-speed I2C controller in the
+	  Exynos5 based Samsung SoCs.
+
 config I2C_GPIO
 	tristate "GPIO-based bitbanging I2C"
 	depends on GPIOLIB
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 385f99d..af6fa37 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -42,6 +42,7 @@  i2c-designware-platform-objs := i2c-designware-platdrv.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
+obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
 obj-$(CONFIG_I2C_GPIO)		+= i2c-gpio.o
 obj-$(CONFIG_I2C_HIGHLANDER)	+= i2c-highlander.o
 obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
diff --git a/drivers/i2c/busses/i2c-exynos5.c b/drivers/i2c/busses/i2c-exynos5.c
new file mode 100644
index 0000000..696d16f
--- /dev/null
+++ b/drivers/i2c/busses/i2c-exynos5.c
@@ -0,0 +1,861 @@ 
+/**
+ * i2c-exynos5.c - Samsung Exynos5 I2C Controller Driver
+ *
+ * Copyright (C) 2013 Samsung Electronics Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/clk.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_i2c.h>
+
+/*
+ * HSI2C controller from Samsung supports 2 modes of operation
+ * 1. Auto mode: Where in master automatically controls the whole transaction
+ * 2. Manual mode: Software controls the transaction by issuing commands
+ *    START, READ, WRITE, STOP, RESTART in I2C_MANUAL_CMD register.
+ *
+ * Operation mode can be selected by setting AUTO_MODE bit in I2C_CONF register
+ *
+ * Special bits are available for both modes of operation to set commands
+ * and for checking transfer status
+ */
+
+/* Register Map */
+#define HSI2C_CTL		0x00
+#define HSI2C_FIFO_CTL		0x04
+#define HSI2C_TRAILIG_CTL	0x08
+#define HSI2C_CLK_CTL		0x0C
+#define HSI2C_CLK_SLOT		0x10
+#define HSI2C_INT_ENABLE	0x20
+#define HSI2C_INT_STATUS	0x24
+#define HSI2C_ERR_STATUS	0x2C
+#define HSI2C_FIFO_STATUS	0x30
+#define HSI2C_TX_DATA		0x34
+#define HSI2C_RX_DATA		0x38
+#define HSI2C_CONF		0x40
+#define HSI2C_AUTO_CONF		0x44
+#define HSI2C_TIMEOUT		0x48
+#define HSI2C_MANUAL_CMD	0x4C
+#define HSI2C_TRANS_STATUS	0x50
+#define HSI2C_TIMING_HS1	0x54
+#define HSI2C_TIMING_HS2	0x58
+#define HSI2C_TIMING_HS3	0x5C
+#define HSI2C_TIMING_FS1	0x60
+#define HSI2C_TIMING_FS2	0x64
+#define HSI2C_TIMING_FS3	0x68
+#define HSI2C_TIMING_SLA	0x6C
+#define HSI2C_ADDR		0x70
+
+/* I2C_CTL Register bits */
+#define HSI2C_FUNC_MODE_I2C			(1u << 0)
+#define HSI2C_MASTER				(1u << 3)
+#define HSI2C_RXCHON				(1u << 6)
+#define HSI2C_TXCHON				(1u << 7)
+#define HSI2C_SW_RST				(1u << 31)
+
+/* I2C_FIFO_CTL Register bits */
+#define HSI2C_RXFIFO_EN				(1u << 0)
+#define HSI2C_TXFIFO_EN				(1u << 1)
+#define HSI2C_FIFO_MAX				(0x40)
+#define HSI2C_RXFIFO_TRIGGER_LEVEL(x)		((x) << 4)
+#define HSI2C_TXFIFO_TRIGGER_LEVEL(x)		((x) << 16)
+/* I2C_TRAILING_CTL Register bits */
+#define HSI2C_TRAILING_COUNT			(0xf)
+
+/* I2C_INT_EN Register bits */
+#define HSI2C_INT_TX_ALMOSTEMPTY_EN		(1u << 0)
+#define HSI2C_INT_RX_ALMOSTFULL_EN		(1u << 1)
+#define HSI2C_INT_TRAILING_EN			(1u << 6)
+#define HSI2C_INT_I2C_EN			(1u << 9)
+
+/* I2C_INT_STAT Register bits */
+#define HSI2C_INT_TX_ALMOSTEMPTY		(1u << 0)
+#define HSI2C_INT_RX_ALMOSTFULL			(1u << 1)
+#define HSI2C_INT_TX_UNDERRUN			(1u << 2)
+#define HSI2C_INT_TX_OVERRUN			(1u << 3)
+#define HSI2C_INT_RX_UNDERRUN			(1u << 4)
+#define HSI2C_INT_RX_OVERRUN			(1u << 5)
+#define HSI2C_INT_TRAILING			(1u << 6)
+#define HSI2C_INT_I2C				(1u << 9)
+#define HSI2C_RX_INT				(HSI2C_INT_RX_ALMOSTFULL | \
+						 HSI2C_INT_RX_UNDERRUN | \
+						 HSI2C_INT_RX_OVERRUN | \
+						 HSI2C_INT_TRAILING)
+
+/* I2C_FIFO_STAT Register bits */
+#define HSI2C_RX_FIFO_EMPTY			(1u << 24)
+#define HSI2C_RX_FIFO_FULL			(1u << 23)
+#define HSI2C_RX_FIFO_LVL(x)			((x >> 16) & 0x7f)
+#define HSI2C_TX_FIFO_EMPTY			(1u << 8)
+#define HSI2C_TX_FIFO_FULL			(1u << 7)
+#define HSI2C_TX_FIFO_LVL(x)			((x >> 0) & 0x7f)
+#define HSI2C_FIFO_EMPTY			(HSI2C_RX_FIFO_EMPTY |	\
+						HSI2C_TX_FIFO_EMPTY)
+
+/* I2C_CONF Register bits */
+#define HSI2C_AUTO_MODE				(1u << 31)
+#define HSI2C_10BIT_ADDR_MODE			(1u << 30)
+#define HSI2C_HS_MODE				(1u << 29)
+
+/* I2C_AUTO_CONF Register bits */
+#define HSI2C_READ_WRITE			(1u << 16)
+#define HSI2C_STOP_AFTER_TRANS			(1u << 17)
+#define HSI2C_MASTER_RUN			(1u << 31)
+
+/* I2C_TIMEOUT Register bits */
+#define HSI2C_TIMEOUT_EN			(1u << 31)
+
+/* I2C_TRANS_STATUS register bits */
+#define HSI2C_MASTER_BUSY			(1u << 17)
+#define HSI2C_SLAVE_BUSY			(1u << 16)
+#define HSI2C_TIMEOUT_AUTO			(1u << 4)
+#define HSI2C_NO_DEV				(1u << 3)
+#define HSI2C_NO_DEV_ACK			(1u << 2)
+#define HSI2C_TRANS_ABORT			(1u << 1)
+#define HSI2C_TRANS_DONE			(1u << 0)
+
+/* I2C_ADDR register bits */
+#define HSI2C_SLV_ADDR_SLV(x)			((x & 0x3ff) << 0)
+#define HSI2C_SLV_ADDR_MAS(x)			((x & 0x3ff) << 10)
+#define HSI2C_MASTER_ID(x)			((x & 0xff) << 24)
+#define MASTER_ID(x)				((x & 0x7) + 0x08)
+
+/*
+ * Controller operating frequency, timing values for operation
+ * are calculated against this frequency
+ */
+#define HSI2C_HS_TX_CLOCK	1000000
+#define HSI2C_FS_TX_CLOCK	100000
+#define HSI2C_HIGH_SPD		1
+#define HSI2C_FAST_SPD		0
+
+#define EXYNOS5_I2C_TIMEOUT (msecs_to_jiffies(1000))
+
+/* timeout for pm runtime autosuspend */
+#define EXYNOS5_I2C_PM_TIMEOUT		1000	/* ms */
+
+struct exynos5_i2c {
+	struct i2c_adapter	adap;
+	unsigned int		suspended:1;
+
+	struct i2c_msg		*msg;
+	struct completion	msg_complete;
+	unsigned int		msg_ptr;
+	unsigned int		msg_len;
+
+	unsigned int		irq;
+
+	void __iomem		*regs;
+	struct clk		*clk;
+	struct device		*dev;
+	int			state;
+
+	/*
+	 * Since the TRANS_DONE bit is cleared on read, and we may read it
+	 * either during an IRQ or after a transaction, keep track of its
+	 * state here.
+	 */
+	int			trans_done;
+
+	/* Controller operating frequency */
+	unsigned int		fs_clock;
+	unsigned int		hs_clock;
+
+	/*
+	 * HSI2C Controller can operate in
+	 * 1. High speed upto 3.4Mbps
+	 * 2. Fast speed upto 1Mbps
+	 */
+	int			speed_mode;
+	int			bus_id;
+};
+
+static const struct of_device_id exynos5_i2c_match[] = {
+	{ .compatible = "samsung,exynos5-hsi2c" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, exynos5_i2c_match);
+
+static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c)
+{
+	writel(readl(i2c->regs + HSI2C_INT_STATUS),
+				i2c->regs + HSI2C_INT_STATUS);
+}
+
+/*
+ * exynos5_i2c_set_timing: updates the registers with appropriate
+ * timing values calculated
+ *
+ * Returns 0 on success, -EINVAL if the cycle length cannot
+ * be calculated.
+ */
+static int exynos5_i2c_set_timing(struct exynos5_i2c *i2c, int mode)
+{
+	u32 i2c_timing_s1;
+	u32 i2c_timing_s2;
+	u32 i2c_timing_s3;
+	u32 i2c_timing_sla;
+	unsigned int t_start_su, t_start_hd;
+	unsigned int t_stop_su;
+	unsigned int t_data_su, t_data_hd;
+	unsigned int t_scl_l, t_scl_h;
+	unsigned int t_sr_release;
+	unsigned int t_ftl_cycle;
+	unsigned int clkin = clk_get_rate(i2c->clk);
+	unsigned int div, utemp0 = 0, utemp1 = 0, clk_cycle;
+	unsigned int op_clk = (mode == HSI2C_HIGH_SPD) ?
+				i2c->hs_clock : i2c->fs_clock;
+
+	/*
+	 * FPCLK / FI2C =
+	 * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
+	 * utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
+	 * utemp1 = (TSCLK_L + TSCLK_H + 2)
+	 */
+	t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
+	utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;
+
+	/* CLK_DIV max is 256 */
+	for (div = 0; div < 256; div++) {
+		utemp1 = utemp0 / (div + 1);
+
+		/*
+		 * SCL_L and SCL_H each has max value of 255
+		 * Hence, For the clk_cycle to the have right value
+		 * utemp1 has to be less then 512 and more than 4.
+		 */
+		if ((utemp1 < 512) && (utemp1 > 4)) {
+			clk_cycle = utemp1 - 2;
+			break;
+		} else if (div == 255) {
+			dev_warn(i2c->dev, "Failed to calculate divisor");
+			return -EINVAL;
+		}
+	}
+
+	t_scl_l = clk_cycle / 2;
+	t_scl_h = clk_cycle / 2;
+	t_start_su = t_scl_l;
+	t_start_hd = t_scl_l;
+	t_stop_su = t_scl_l;
+	t_data_su = t_scl_l / 2;
+	t_data_hd = t_scl_l / 2;
+	t_sr_release = clk_cycle;
+
+	i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
+	i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
+	i2c_timing_s3 = div << 16 | t_sr_release << 0;
+	i2c_timing_sla = t_data_hd << 0;
+
+	dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
+		t_start_su, t_start_hd, t_stop_su);
+	dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
+		t_data_su, t_scl_l, t_scl_h);
+	dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
+		div, t_sr_release);
+	dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);
+
+	if (mode == HSI2C_HIGH_SPD) {
+		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
+		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
+		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
+	} else {
+		writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
+		writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
+		writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
+	}
+	writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);
+
+	return 0;
+}
+
+static int exynos5_hsi2c_clock_setup(struct exynos5_i2c *i2c)
+{
+	/*
+	 * Configure the Fast speed timing values
+	 * Even the High Speed mode initially starts with Fast mode
+	 */
+	if (exynos5_i2c_set_timing(i2c, HSI2C_FAST_SPD)) {
+		dev_err(i2c->dev, "HSI2C FS Clock set up failed\n");
+		return -EINVAL;
+	}
+
+	/* configure the High speed timing values */
+	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
+		if (exynos5_i2c_set_timing(i2c, HSI2C_HIGH_SPD)) {
+			dev_err(i2c->dev, "HSI2C HS Clock set up failed\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * exynos5_i2c_init: configures the controller for I2C functionality
+ * Programs I2C controller for Master mode operation
+ */
+static void exynos5_i2c_init(struct exynos5_i2c *i2c)
+{
+	u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
+
+	writel((HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
+					i2c->regs + HSI2C_CTL);
+	writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);
+
+	if (i2c->speed_mode == HSI2C_HIGH_SPD) {
+		writel(HSI2C_MASTER_ID(MASTER_ID(i2c->bus_id)),
+					i2c->regs + HSI2C_ADDR);
+		i2c_conf |= HSI2C_HS_MODE;
+	}
+
+	writel(i2c_conf | HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
+}
+
+static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
+{
+	u32 i2c_ctl;
+
+	/* Set and clear the bit for reset */
+	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
+	i2c_ctl |= HSI2C_SW_RST;
+	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
+
+	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
+	i2c_ctl &= ~HSI2C_SW_RST;
+	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
+
+	/* We don't expect calculations to fail during the run */
+	exynos5_hsi2c_clock_setup(i2c);
+	/* Initialize the configure registers */
+	exynos5_i2c_init(i2c);
+}
+
+/*
+ * exynos5_i2c_irq: top level IRQ servicing routine
+ *
+ * INT_STATUS registers gives the interrupt details. Further,
+ * FIFO_STATUS or TRANS_STATUS registers are to be check for detailed
+ * state of the bus.
+ */
+static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
+{
+	struct exynos5_i2c *i2c = dev_id;
+	u32 fifo_level, int_status, fifo_status, trans_status;
+	unsigned char byte;
+	int len = 0;
+
+	i2c->state = -EINVAL;
+
+	int_status = readl(i2c->regs + HSI2C_INT_STATUS);
+	fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
+
+	if (int_status & HSI2C_INT_I2C) {
+		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
+		if (trans_status & HSI2C_NO_DEV_ACK) {
+			dev_dbg(i2c->dev, "No ACK from device\n");
+			i2c->state = -ENXIO;
+		} else if (trans_status & HSI2C_NO_DEV) {
+			dev_dbg(i2c->dev, "No device\n");
+			i2c->state = -ENXIO;
+		} else if (trans_status & HSI2C_TRANS_ABORT) {
+			dev_dbg(i2c->dev, "Deal with arbitration lose\n");
+			i2c->state = -EAGAIN;
+		} else if (trans_status & HSI2C_TIMEOUT_AUTO) {
+			dev_dbg(i2c->dev, "Accessing device timed out\n");
+			i2c->state = -EAGAIN;
+		} else if (trans_status & HSI2C_TRANS_DONE) {
+			i2c->trans_done = 1;
+			i2c->state = 0;
+		}
+	}
+	/* TX_ALMOSTEMPTY can happen along with HSI2C_INT_I2C */
+	else if (int_status &
+			(HSI2C_INT_TX_UNDERRUN | HSI2C_INT_TX_ALMOSTEMPTY)) {
+		fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);
+
+		/* To support probing the devices for detection */
+		if (i2c->msg->len == 0) {
+			i2c->state = -ENXIO;
+			goto stop;
+		}
+
+		len = HSI2C_FIFO_MAX - fifo_level;
+		if (len > i2c->msg->len)
+			len = i2c->msg->len;
+
+		i2c->msg_len += len;
+		while (len > 0) {
+			byte = i2c->msg->buf[i2c->msg_ptr++];
+			writel(byte, i2c->regs + HSI2C_TX_DATA);
+			len--;
+		}
+		i2c->state = 0;
+		goto stop;
+	}
+	/* If TX FIFO is full (give chance to clear) */
+	else if (int_status & HSI2C_INT_TX_OVERRUN)
+		i2c->state = 0;
+
+	if (int_status & (HSI2C_INT_RX_OVERRUN | HSI2C_INT_TRAILING |
+		HSI2C_INT_RX_UNDERRUN | HSI2C_INT_RX_ALMOSTFULL)) {
+		fifo_level = HSI2C_RX_FIFO_LVL(fifo_status);
+
+		if (fifo_level >= i2c->msg->len)
+			len = i2c->msg->len;
+		else
+			len = fifo_level;
+
+		i2c->msg_len += len;
+		while (len > 0) {
+			byte = (unsigned char)
+				readl(i2c->regs + HSI2C_RX_DATA);
+			i2c->msg->buf[i2c->msg_ptr++] = byte;
+			len--;
+		}
+		i2c->state = 0;
+	}
+
+
+ stop:
+	if ((i2c->msg_len == i2c->msg->len) || (i2c->state < 0)) {
+		writel(0, i2c->regs + HSI2C_INT_ENABLE);
+		complete(&i2c->msg_complete);
+	}
+
+	exynos5_i2c_clr_pend_irq(i2c);
+
+	return IRQ_HANDLED;
+}
+
+/*
+ * exynos5_i2c_wait_bus_idle
+ *
+ * Wait for the transaction to complete (indicated by the TRANS_DONE bit
+ * being set), and, if this is the last message in a transfer, wait for the
+ * MASTER_BUSY bit to be cleared.
+ *
+ * Returns -EBUSY if the bus cannot be brought to idle
+ */
+static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c, int stop)
+{
+	unsigned long stop_time;
+	u32 trans_status;
+
+	/* wait for 100 milli seconds for the bus to be idle */
+	stop_time = jiffies + msecs_to_jiffies(100) + 1;
+	do {
+		trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
+		if (trans_status & HSI2C_TRANS_DONE)
+			i2c->trans_done = 1;
+		/*
+		 * Only wait for MASTER_BUSY to be cleared if this is the last
+		 * message.
+		 */
+		if ((!stop || !(trans_status & HSI2C_MASTER_BUSY)) &&
+		    i2c->trans_done)
+			return 0;
+
+		usleep_range(50, 200);
+	} while (time_before(jiffies, stop_time));
+
+	return -EBUSY;
+}
+
+/*
+ * exynos5_i2c_message_start: Configures the bus and starts the xfer
+ * i2c: struct exynos5_i2c pointer for the current bus
+ * stop: Enables stop after transfer if set. Set for last transfer of
+ *       in the list of messages.
+ *
+ * Configures the bus for read/write function
+ * Sets chip address to talk to, message length to be sent.
+ * Enables appropriate interrupts and sends start xfer command.
+ */
+static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
+{
+	u32 i2c_ctl;
+	u32 int_en = HSI2C_INT_I2C_EN;
+	u32 i2c_auto_conf = 0;
+	u32 fifo_ctl;
+	u32 i2c_timeout;
+
+	/*
+	 * When the message length is > FIFO depth, set the FIFO trigger
+	 * at FIFO_MAX - 4. Just for ease of handling.
+	 */
+	unsigned short len = (i2c->msg->len > HSI2C_FIFO_MAX) ?
+					(HSI2C_FIFO_MAX - 4) : i2c->msg->len;
+
+	/* Clear to enable Timeout */
+	i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);
+	i2c_timeout &= ~HSI2C_TIMEOUT_EN;
+	writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);
+
+	fifo_ctl = HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN;
+	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
+
+	i2c_ctl = readl(i2c->regs + HSI2C_CTL);
+	i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
+	if (i2c->msg->flags & I2C_M_RD) {
+		i2c_ctl |= HSI2C_RXCHON;
+
+		i2c_auto_conf |= HSI2C_READ_WRITE;
+
+		fifo_ctl |= HSI2C_RXFIFO_TRIGGER_LEVEL(len);
+		int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
+			HSI2C_INT_TRAILING_EN);
+	} else {
+		i2c_ctl |= HSI2C_TXCHON;
+
+		fifo_ctl |= HSI2C_TXFIFO_TRIGGER_LEVEL(len);
+		int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
+	}
+
+	if (stop == 1)
+		i2c_auto_conf |= HSI2C_STOP_AFTER_TRANS;
+
+	writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);
+
+	writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
+	writel(i2c_ctl, i2c->regs + HSI2C_CTL);
+
+	/* In auto mode the length of xfer cannot be 0 */
+	if (i2c->msg->len == 0)
+		i2c_auto_conf |= 0x1;
+	else
+		i2c_auto_conf |= i2c->msg->len;
+
+	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
+
+	/* Start data transfer in Master mode */
+	i2c_auto_conf = readl(i2c->regs + HSI2C_AUTO_CONF);
+	i2c_auto_conf |= HSI2C_MASTER_RUN;
+	writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
+
+	writel(int_en, i2c->regs + HSI2C_INT_ENABLE);
+}
+
+static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
+			      struct i2c_msg *msgs, int stop)
+{
+	unsigned long timeout;
+	int ret;
+
+	i2c->msg = msgs;
+	i2c->msg_ptr = 0;
+	i2c->msg_len = 0;
+	i2c->trans_done = 0;
+
+	INIT_COMPLETION(i2c->msg_complete);
+
+	exynos5_i2c_message_start(i2c, stop);
+
+	timeout = wait_for_completion_timeout
+		(&i2c->msg_complete, EXYNOS5_I2C_TIMEOUT);
+	if (timeout == 0) {
+		exynos5_i2c_reset(i2c);
+		dev_warn(i2c->dev, "%s timeout\n",
+			 (msgs->flags & I2C_M_RD) ? "rx" : "tx");
+		return timeout;
+	}
+
+	ret = i2c->state;
+
+	if (ret == -EAGAIN) {
+		exynos5_i2c_reset(i2c);
+		return ret;
+	}
+
+	/*
+	 * If this is the last message to be transfered (stop == 1)
+	 * Then check if the bus can be brought back to idle.
+	 *
+	 * Return -EBUSY if the bus still busy.
+	 */
+	if (exynos5_i2c_wait_bus_idle(i2c, stop))
+		return -EBUSY;
+
+	/* Return the state as in interrupt routine */
+	return ret;
+}
+
+static int exynos5_i2c_xfer(struct i2c_adapter *adap,
+			struct i2c_msg *msgs, int num)
+{
+	struct exynos5_i2c *i2c = (struct exynos5_i2c *)adap->algo_data;
+	struct i2c_msg *msgs_ptr = msgs;
+	int i = 0;
+	int ret = 0, ret_pm;
+	int stop = 0;
+
+	if (i2c->suspended) {
+		dev_err(i2c->dev, "HS-I2C is not initialzed.\n");
+		return -EIO;
+	}
+
+	ret_pm = pm_runtime_get_sync(i2c->dev);
+	if (IS_ERR_VALUE(ret_pm)) {
+		ret = -EIO;
+		goto out;
+	}
+
+	clk_prepare_enable(i2c->clk);
+
+	for (i = 0; i < num; i++) {
+		stop = (i == num - 1);
+
+		ret = exynos5_i2c_xfer_msg(i2c, msgs_ptr, stop);
+		msgs_ptr++;
+
+		if (ret < 0)
+			goto out;
+	}
+
+	if (i == num) {
+		ret = num;
+	} else {
+		/* Only one message, cannot access the device */
+		if (i == 1)
+			ret = -EREMOTEIO;
+		else
+			ret = i;
+
+		dev_warn(i2c->dev, "xfer message failed\n");
+	}
+
+ out:
+	clk_disable_unprepare(i2c->clk);
+	pm_runtime_mark_last_busy(i2c->dev);
+	pm_runtime_put_autosuspend(i2c->dev);
+	return ret;
+}
+
+static u32 exynos5_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
+}
+
+static const struct i2c_algorithm exynos5_i2c_algorithm = {
+	.master_xfer		= exynos5_i2c_xfer,
+	.functionality		= exynos5_i2c_func,
+};
+
+static int exynos5_i2c_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct exynos5_i2c *i2c;
+	struct resource *mem;
+	unsigned int op_clock;
+	int ret;
+
+	if (!np) {
+		dev_err(&pdev->dev, "no device node\n");
+		return -ENOENT;
+	}
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
+	if (!i2c) {
+		dev_err(&pdev->dev, "no memory for state\n");
+		return -ENOMEM;
+	}
+
+	if (of_property_read_u32(np, "clock-frequency", &op_clock)) {
+		i2c->speed_mode = HSI2C_FAST_SPD;
+		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
+	}
+
+	if (op_clock >= HSI2C_HS_TX_CLOCK) {
+		i2c->speed_mode = HSI2C_HIGH_SPD;
+		i2c->fs_clock = HSI2C_FS_TX_CLOCK;
+		i2c->hs_clock = op_clock;
+	} else {
+		i2c->speed_mode = HSI2C_FAST_SPD;
+		i2c->fs_clock = op_clock;
+	}
+
+	strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
+	i2c->adap.owner   = THIS_MODULE;
+	i2c->adap.algo    = &exynos5_i2c_algorithm;
+	i2c->adap.retries = 2;
+
+	i2c->dev = &pdev->dev;
+	i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
+	if (IS_ERR(i2c->clk)) {
+		dev_err(&pdev->dev, "cannot get clock\n");
+		return -ENOENT;
+	}
+
+	clk_prepare_enable(i2c->clk);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	i2c->regs = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(i2c->regs)) {
+		ret = PTR_ERR(i2c->regs);
+		goto err_clk;
+	}
+
+	i2c->adap.dev.of_node = np;
+	i2c->adap.algo_data = i2c;
+	i2c->adap.dev.parent = &pdev->dev;
+
+	/* Clear pending interrupts from u-boot or misc causes */
+	exynos5_i2c_clr_pend_irq(i2c);
+
+	init_completion(&i2c->msg_complete);
+
+	i2c->irq = ret = irq_of_parse_and_map(np, 0);
+	if (ret <= 0) {
+		dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
+		ret = -EINVAL;
+		goto err_clk;
+	}
+
+	ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
+				0, dev_name(&pdev->dev), i2c);
+
+	if (ret != 0) {
+		dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
+		goto err_clk;
+	}
+
+	/*
+	 * TODO: Use private lock to avoid race conditions as
+	 * mentioned in pm_runtime.txt
+	 */
+	pm_runtime_enable(i2c->dev);
+	pm_runtime_set_autosuspend_delay(i2c->dev, EXYNOS5_I2C_PM_TIMEOUT);
+	pm_runtime_use_autosuspend(i2c->dev);
+
+	ret = pm_runtime_get_sync(i2c->dev);
+	if (IS_ERR_VALUE(ret))
+		goto err_clk;
+
+	ret = exynos5_hsi2c_clock_setup(i2c);
+	if (ret)
+		goto err_pm;
+
+	i2c->bus_id = of_alias_get_id(i2c->adap.dev.of_node, "hsi2c");
+
+	exynos5_i2c_init(i2c);
+
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
+		goto err_pm;
+	}
+
+	of_i2c_register_devices(&i2c->adap);
+	platform_set_drvdata(pdev, i2c);
+
+	clk_disable_unprepare(i2c->clk);
+	pm_runtime_mark_last_busy(i2c->dev);
+	pm_runtime_put_autosuspend(i2c->dev);
+
+	return 0;
+
+ err_pm:
+	pm_runtime_put(i2c->dev);
+	pm_runtime_disable(&pdev->dev);
+ err_clk:
+	clk_disable_unprepare(i2c->clk);
+	return ret;
+}
+
+static int exynos5_i2c_remove(struct platform_device *pdev)
+{
+	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
+	int ret;
+
+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (IS_ERR_VALUE(ret))
+		return ret;
+
+	i2c_del_adapter(&i2c->adap);
+
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	clk_disable_unprepare(i2c->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+static int exynos5_i2c_suspend_noirq(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c->suspended = 1;
+
+	return 0;
+}
+
+static int exynos5_i2c_resume_noirq(struct device *dev)
+{
+	struct platform_device *pdev = to_platform_device(dev);
+	struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
+	int ret = 0;
+
+	clk_prepare_enable(i2c->clk);
+
+	ret = exynos5_hsi2c_clock_setup(i2c);
+	if (ret) {
+		clk_disable_unprepare(i2c->clk);
+		return ret;
+	}
+
+	exynos5_i2c_init(i2c);
+	clk_disable_unprepare(i2c->clk);
+	i2c->suspended = 0;
+
+	return 0;
+}
+
+static const struct dev_pm_ops exynos5_i2c_dev_pm_ops = {
+	.suspend_noirq = exynos5_i2c_suspend_noirq,
+	.resume_noirq	= exynos5_i2c_resume_noirq,
+};
+
+#define EXYNOS5_DEV_PM_OPS (&exynos5_i2c_dev_pm_ops)
+#else
+#define EXYNOS5_DEV_PM_OPS NULL
+#endif
+
+static struct platform_driver exynos5_i2c_driver = {
+	.probe		= exynos5_i2c_probe,
+	.remove		= exynos5_i2c_remove,
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "exynos5-hsi2c",
+		.pm	= EXYNOS5_DEV_PM_OPS,
+		.of_match_table = exynos5_i2c_match,
+	},
+};
+
+module_platform_driver(exynos5_i2c_driver);
+
+MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
+MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen@samsung.com>");
+MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko@samsung.com>");
+MODULE_LICENSE("GPL v2");