[v4,2/2] i2c: Add Spreadtrum I2C controller driver

This patch adds the I2C controller driver for Spreadtrum SC9860 platform.

Signed-off-by: Baolin Wang <baolin.wang@spreadtrum.com>
---
Changes since v3:
 - Use SPDX-License-Identifier tag instead.

Changes since v2:
 - Remove some redundant comments and parens.
 - Define macros instead of magic number.
 - Add some comments to explain clock formula.
 - Change of_clk_get_by_name() to devm_clk_get().
 - Deal with other frequency.
 - Change register definiton to low case.
 - Change is_last_msg to boolean.
 - Other optimization.

Changes sice v1:
 - Power on I2C device in probe().
 - Remove redundant macros and usb __maybe_unused.
 - Remove redundant 'of_match_ptr'.
 - Modify return values and check the return value for 'clk_prepare_enable'.
---
 drivers/i2c/busses/Kconfig    |    7 +
 drivers/i2c/busses/Makefile   |    1 +
 drivers/i2c/busses/i2c-sprd.c |  676 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 684 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-sprd.c

On Thu, Jul 6, 2017 at 11:47 AM, Baolin Wang <baolin.wang@spreadtrum.com> wrote:
> This patch adds the I2C controller driver for Spreadtrum SC9860 platform.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

P.S. There is still room for improvement, though it either requires
additional changes to the kernel or minor on this stage. Would be done
later.

> Signed-off-by: Baolin Wang <baolin.wang@spreadtrum.com>
> ---
> Changes since v3:
>  - Use SPDX-License-Identifier tag instead.
>
> Changes since v2:
>  - Remove some redundant comments and parens.
>  - Define macros instead of magic number.
>  - Add some comments to explain clock formula.
>  - Change of_clk_get_by_name() to devm_clk_get().
>  - Deal with other frequency.
>  - Change register definiton to low case.
>  - Change is_last_msg to boolean.
>  - Other optimization.
>
> Changes sice v1:
>  - Power on I2C device in probe().
>  - Remove redundant macros and usb __maybe_unused.
>  - Remove redundant 'of_match_ptr'.
>  - Modify return values and check the return value for 'clk_prepare_enable'.
> ---
>  drivers/i2c/busses/Kconfig    |    7 +
>  drivers/i2c/busses/Makefile   |    1 +
>  drivers/i2c/busses/i2c-sprd.c |  676 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 684 insertions(+)
>  create mode 100644 drivers/i2c/busses/i2c-sprd.c
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 8adc0f1..86476b9 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -877,6 +877,13 @@ config I2C_SIRF
>           This driver can also be built as a module.  If so, the module
>           will be called i2c-sirf.
>
> +config I2C_SPRD
> +       bool "Spreadtrum I2C interface"
> +       depends on ARCH_SPRD
> +       help
> +         If you say yes to this option, support will be included for the
> +         Spreadtrum I2C interface.
> +
>  config I2C_ST
>         tristate "STMicroelectronics SSC I2C support"
>         depends on ARCH_STI
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 30b6085..dd46c21 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -84,6 +84,7 @@ obj-$(CONFIG_I2C_SH7760)      += i2c-sh7760.o
>  obj-$(CONFIG_I2C_SH_MOBILE)    += i2c-sh_mobile.o
>  obj-$(CONFIG_I2C_SIMTEC)       += i2c-simtec.o
>  obj-$(CONFIG_I2C_SIRF)         += i2c-sirf.o
> +obj-$(CONFIG_I2C_SPRD)         += i2c-sprd.o
>  obj-$(CONFIG_I2C_ST)           += i2c-st.o
>  obj-$(CONFIG_I2C_STM32F4)      += i2c-stm32f4.o
>  obj-$(CONFIG_I2C_STU300)       += i2c-stu300.o
> diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
> new file mode 100644
> index 0000000..4193f4d
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-sprd.c
> @@ -0,0 +1,676 @@
> +/*
> + * Copyright (C) 2017 Spreadtrum Communications Inc.
> + *
> + * SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/i2c.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +
> +#define I2C_CTL                        0x00
> +#define I2C_ADDR_CFG           0x04
> +#define I2C_COUNT              0x08
> +#define I2C_RX                 0x0c
> +#define I2C_TX                 0x10
> +#define I2C_STATUS             0x14
> +#define I2C_HSMODE_CFG         0x18
> +#define I2C_VERSION            0x1c
> +#define ADDR_DVD0              0x20
> +#define ADDR_DVD1              0x24
> +#define ADDR_STA0_DVD          0x28
> +#define ADDR_RST               0x2c
> +
> +/* I2C_CTL */
> +#define STP_EN                 BIT(20)
> +#define FIFO_AF_LVL_MASK       GENMASK(19, 16)
> +#define FIFO_AF_LVL            16
> +#define FIFO_AE_LVL_MASK       GENMASK(15, 12)
> +#define FIFO_AE_LVL            12
> +#define I2C_DMA_EN             BIT(11)
> +#define FULL_INTEN             BIT(10)
> +#define EMPTY_INTEN            BIT(9)
> +#define I2C_DVD_OPT            BIT(8)
> +#define I2C_OUT_OPT            BIT(7)
> +#define I2C_TRIM_OPT           BIT(6)
> +#define I2C_HS_MODE            BIT(4)
> +#define I2C_MODE               BIT(3)
> +#define I2C_EN                 BIT(2)
> +#define I2C_INT_EN             BIT(1)
> +#define I2C_START              BIT(0)
> +
> +/* I2C_STATUS */
> +#define SDA_IN                 BIT(21)
> +#define SCL_IN                 BIT(20)
> +#define FIFO_FULL              BIT(4)
> +#define FIFO_EMPTY             BIT(3)
> +#define I2C_INT                        BIT(2)
> +#define I2C_RX_ACK             BIT(1)
> +#define I2C_BUSY               BIT(0)
> +
> +/* ADDR_RST */
> +#define I2C_RST                        BIT(0)
> +
> +#define I2C_FIFO_DEEP          12
> +#define I2C_FIFO_FULL_THLD     15
> +#define I2C_FIFO_EMPTY_THLD    4
> +#define I2C_DATA_STEP          8
> +#define I2C_ADDR_DVD0_CALC(high, low)  \
> +       ((((high) & GENMASK(15, 0)) << 16) | ((low) & GENMASK(15, 0)))
> +#define I2C_ADDR_DVD1_CALC(high, low)  \
> +       (((high) & GENMASK(31, 16)) | (((low) & GENMASK(31, 16)) >> 16))
> +
> +/* timeout (ms) for pm runtime autosuspend */
> +#define SPRD_I2C_PM_TIMEOUT    1000
> +
> +/* SPRD i2c data structure */
> +struct sprd_i2c {
> +       struct i2c_adapter adap;
> +       struct device *dev;
> +       void __iomem *base;
> +       struct i2c_msg *msg;
> +       struct clk *clk;
> +       unsigned int src_clk;
> +       unsigned int bus_freq;
> +       struct completion complete;
> +       u8 *buf;
> +       u16 count;
> +       int irq;
> +       int err;
> +};
> +
> +static void sprd_i2c_dump_reg(struct sprd_i2c *i2c_dev)
> +{
> +       dev_err(&i2c_dev->adap.dev, ": ======dump i2c-%d reg=======\n",
> +               i2c_dev->adap.nr);
> +       dev_err(&i2c_dev->adap.dev, ": I2C_CTRL:0x%x\n",
> +               readl(i2c_dev->base + I2C_CTL));
> +       dev_err(&i2c_dev->adap.dev, ": I2C_ADDR_CFG:0x%x\n",
> +               readl(i2c_dev->base + I2C_ADDR_CFG));
> +       dev_err(&i2c_dev->adap.dev, ": I2C_COUNT:0x%x\n",
> +               readl(i2c_dev->base + I2C_COUNT));
> +       dev_err(&i2c_dev->adap.dev, ": I2C_RX:0x%x\n",
> +               readl(i2c_dev->base + I2C_RX));
> +       dev_err(&i2c_dev->adap.dev, ": I2C_STATUS:0x%x\n",
> +               readl(i2c_dev->base + I2C_STATUS));
> +       dev_err(&i2c_dev->adap.dev, ": ADDR_DVD0:0x%x\n",
> +               readl(i2c_dev->base + ADDR_DVD0));
> +       dev_err(&i2c_dev->adap.dev, ": ADDR_DVD1:0x%x\n",
> +               readl(i2c_dev->base + ADDR_DVD1));
> +       dev_err(&i2c_dev->adap.dev, ": ADDR_STA0_DVD:0x%x\n",
> +               readl(i2c_dev->base + ADDR_STA0_DVD));
> +       dev_err(&i2c_dev->adap.dev, ": ADDR_RST:0x%x\n",
> +               readl(i2c_dev->base + ADDR_RST));
> +}
> +
> +static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count)
> +{
> +       writel(count, i2c_dev->base + I2C_COUNT);
> +}
> +
> +static void sprd_i2c_send_stop(struct sprd_i2c *i2c_dev, int stop)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       if (stop)
> +               writel(tmp & ~STP_EN, i2c_dev->base + I2C_CTL);
> +       else
> +               writel(tmp | STP_EN, i2c_dev->base + I2C_CTL);
> +}
> +
> +static void sprd_i2c_clear_start(struct sprd_i2c *i2c_dev)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       writel(tmp & ~I2C_START, i2c_dev->base + I2C_CTL);
> +}
> +
> +static void sprd_i2c_clear_ack(struct sprd_i2c *i2c_dev)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
> +
> +       writel(tmp & ~I2C_RX_ACK, i2c_dev->base + I2C_STATUS);
> +}
> +
> +static void sprd_i2c_clear_irq(struct sprd_i2c *i2c_dev)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
> +
> +       writel(tmp & ~I2C_INT, i2c_dev->base + I2C_STATUS);
> +}
> +
> +static void sprd_i2c_reset_fifo(struct sprd_i2c *i2c_dev)
> +{
> +       writel(I2C_RST, i2c_dev->base + ADDR_RST);
> +}
> +
> +static void sprd_i2c_set_devaddr(struct sprd_i2c *i2c_dev, struct i2c_msg *m)
> +{
> +       writel(m->addr << 1, i2c_dev->base + I2C_ADDR_CFG);
> +}
> +
> +static void sprd_i2c_write_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u32 len)
> +{
> +       u32 i;
> +
> +       for (i = 0; i < len; i++)
> +               writeb(buf[i], i2c_dev->base + I2C_TX);
> +}
> +
> +static void sprd_i2c_read_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u16 len)
> +{
> +       u32 i;
> +
> +       for (i = 0; i < len; i++)
> +               buf[i] = readb(i2c_dev->base + I2C_RX);
> +}
> +
> +static void sprd_i2c_set_full_thld(struct sprd_i2c *i2c_dev, u32 full_thld)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       tmp &= ~FIFO_AF_LVL_MASK;
> +       tmp |= full_thld << FIFO_AF_LVL;
> +       writel(tmp, i2c_dev->base + I2C_CTL);
> +};
> +
> +static void sprd_i2c_set_empty_thld(struct sprd_i2c *i2c_dev, u32 empty_thld)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       tmp &= ~FIFO_AE_LVL_MASK;
> +       tmp |= empty_thld << FIFO_AE_LVL;
> +       writel(tmp, i2c_dev->base + I2C_CTL);
> +};
> +
> +static void sprd_i2c_set_fifo_full_int(struct sprd_i2c *i2c_dev, int enable)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       if (enable)
> +               tmp |= FULL_INTEN;
> +       else
> +               tmp &= ~FULL_INTEN;
> +
> +       writel(tmp, i2c_dev->base + I2C_CTL);
> +};
> +
> +static void sprd_i2c_set_fifo_empty_int(struct sprd_i2c *i2c_dev, int enable)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       if (enable)
> +               tmp |= EMPTY_INTEN;
> +       else
> +               tmp &= ~EMPTY_INTEN;
> +
> +       writel(tmp, i2c_dev->base + I2C_CTL);
> +};
> +
> +static void sprd_i2c_opt_start(struct sprd_i2c *i2c_dev)
> +{
> +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> +
> +       writel(tmp | I2C_START, i2c_dev->base + I2C_CTL);
> +}
> +
> +static void sprd_i2c_opt_mode(struct sprd_i2c *i2c_dev, int rw)
> +{
> +       unsigned int cmd = readl(i2c_dev->base + I2C_CTL) & ~I2C_MODE;
> +
> +       writel(cmd | rw << 3, i2c_dev->base + I2C_CTL);
> +}
> +
> +static void sprd_i2c_data_transfer(struct sprd_i2c *i2c_dev)
> +{
> +       u32 i2c_count = i2c_dev->count;
> +       u32 need_tran = i2c_count <= I2C_FIFO_DEEP ? i2c_count : I2C_FIFO_DEEP;
> +       struct i2c_msg *msg = i2c_dev->msg;
> +
> +       if (msg->flags & I2C_M_RD) {
> +               sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, I2C_FIFO_FULL_THLD);
> +               i2c_dev->count -= I2C_FIFO_FULL_THLD;
> +               i2c_dev->buf += I2C_FIFO_FULL_THLD;
> +
> +               /*
> +                * If the read data count is larger than rx fifo full threshold,
> +                * we should enable the rx fifo full interrupt to read data
> +                * again.
> +                */
> +               if (i2c_dev->count >= I2C_FIFO_FULL_THLD)
> +                       sprd_i2c_set_fifo_full_int(i2c_dev, 1);
> +       } else {
> +               sprd_i2c_write_bytes(i2c_dev, i2c_dev->buf, need_tran);
> +               i2c_dev->buf += need_tran;
> +               i2c_dev->count -= need_tran;
> +
> +               /*
> +                * If the write data count is arger than tx fifo depth which
> +                * means we can not write all data in one time, then we should
> +                * enable the tx fifo empty interrupt to write again.
> +                */
> +               if (i2c_count > I2C_FIFO_DEEP)
> +                       sprd_i2c_set_fifo_empty_int(i2c_dev, 1);
> +       }
> +}
> +
> +static int sprd_i2c_handle_msg(struct i2c_adapter *i2c_adap,
> +                              struct i2c_msg *msg, bool is_last_msg)
> +{
> +       struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
> +
> +       i2c_dev->msg = msg;
> +       i2c_dev->buf = msg->buf;
> +       i2c_dev->count = msg->len;
> +
> +       reinit_completion(&i2c_dev->complete);
> +       sprd_i2c_reset_fifo(i2c_dev);
> +       sprd_i2c_set_devaddr(i2c_dev, msg);
> +       sprd_i2c_set_count(i2c_dev, msg->len);
> +
> +       if ((msg->flags & I2C_M_RD)) {
> +               sprd_i2c_opt_mode(i2c_dev, 1);
> +               sprd_i2c_send_stop(i2c_dev, 1);
> +       } else {
> +               sprd_i2c_opt_mode(i2c_dev, 0);
> +               sprd_i2c_send_stop(i2c_dev, !!is_last_msg);
> +       }
> +
> +       /*
> +        * We should enable rx fifo full interrupt to get data when receiving
> +        * full data.
> +        */
> +       if ((msg->flags & I2C_M_RD))
> +               sprd_i2c_set_fifo_full_int(i2c_dev, 1);
> +       else
> +               sprd_i2c_data_transfer(i2c_dev);
> +
> +       sprd_i2c_opt_start(i2c_dev);
> +
> +       wait_for_completion(&i2c_dev->complete);
> +
> +       return i2c_dev->err;
> +}
> +
> +static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap,
> +                               struct i2c_msg *msgs, int num)
> +{
> +       struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
> +       int im, ret;
> +
> +       ret = pm_runtime_get_sync(i2c_dev->dev);
> +       if (ret < 0)
> +               return ret;
> +
> +       for (im = 0; im < num - 1; im++) {
> +               ret = sprd_i2c_handle_msg(i2c_adap, &msgs[im], 0);
> +               if (ret)
> +                       goto err_msg;
> +       }
> +
> +       ret = sprd_i2c_handle_msg(i2c_adap, &msgs[im++], 1);
> +
> +err_msg:
> +       pm_runtime_mark_last_busy(i2c_dev->dev);
> +       pm_runtime_put_autosuspend(i2c_dev->dev);
> +
> +       return ret < 0 ? ret : im;
> +}
> +
> +static u32 sprd_i2c_func(struct i2c_adapter *adap)
> +{
> +       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static const struct i2c_algorithm sprd_i2c_algo = {
> +       .master_xfer = sprd_i2c_master_xfer,
> +       .functionality = sprd_i2c_func,
> +};
> +
> +static void sprd_i2c_set_clk(struct sprd_i2c *i2c_dev, unsigned int freq)
> +{
> +       u32 apb_clk = i2c_dev->src_clk;
> +       /*
> +        * From I2C databook, the prescale calculation formula:
> +        * prescale = freq_i2c / (4 * freq_scl) - 1;
> +        */
> +       u32 i2c_dvd = apb_clk / (4 * freq) - 1;
> +       /*
> +        * From I2C databook, the high period of SCL clock is recommended as
> +        * 40% (2/5), and the low period of SCL clock is recommended as 60%
> +        * (3/5), then the formula should be:
> +        * high = (prescale * 2 * 2) / 5
> +        * low = (prescale * 2 * 3) / 5
> +        */
> +       u32 high = ((i2c_dvd << 1) * 2) / 5;
> +       u32 low = ((i2c_dvd << 1) * 3) / 5;
> +       u32 div0 = I2C_ADDR_DVD0_CALC(high, low);
> +       u32 div1 = I2C_ADDR_DVD1_CALC(high, low);
> +
> +       writel(div0, i2c_dev->base + ADDR_DVD0);
> +       writel(div1, i2c_dev->base + ADDR_DVD1);
> +
> +       /* Start hold timing = hold time(us) * source clock */
> +       if (freq == 400000)
> +               writel((6 * apb_clk) / 10000000, i2c_dev->base + ADDR_STA0_DVD);
> +       else if (freq == 100000)
> +               writel((4 * apb_clk) / 1000000, i2c_dev->base + ADDR_STA0_DVD);
> +}
> +
> +static void sprd_i2c_enable(struct sprd_i2c *i2c_dev)
> +{
> +       unsigned int tmp = I2C_DVD_OPT;
> +
> +       writel(tmp, i2c_dev->base + I2C_CTL);
> +
> +       sprd_i2c_set_full_thld(i2c_dev, I2C_FIFO_FULL_THLD);
> +       sprd_i2c_set_empty_thld(i2c_dev, I2C_FIFO_EMPTY_THLD);
> +
> +       sprd_i2c_set_clk(i2c_dev, i2c_dev->bus_freq);
> +       sprd_i2c_reset_fifo(i2c_dev);
> +       sprd_i2c_clear_irq(i2c_dev);
> +
> +       tmp = readl(i2c_dev->base + I2C_CTL);
> +       writel(tmp | I2C_EN | I2C_INT_EN, i2c_dev->base + I2C_CTL);
> +}
> +
> +static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
> +{
> +       struct sprd_i2c *i2c_dev = dev_id;
> +       struct i2c_msg *msg = i2c_dev->msg;
> +       int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
> +       u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
> +       u32 i2c_tran;
> +
> +       if (msg->flags & I2C_M_RD)
> +               i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
> +       else
> +               i2c_tran = i2c_count;
> +
> +       /*
> +        * If we got one ACK from slave when writing data, and we did not
> +        * finish this transmission (i2c_tran is not zero), then we should
> +        * continue to write data.
> +        *
> +        * For reading data, ack is always 0, if i2c_tran is not 0 which
> +        * means we still need to contine to read data from slave.
> +        */
> +       if (i2c_tran && !ack) {
> +               sprd_i2c_data_transfer(i2c_dev);
> +               return IRQ_HANDLED;
> +       }
> +
> +       i2c_dev->err = 0;
> +
> +       /*
> +        * If we did not get one ACK from slave when writing data, we should
> +        * dump all registers to check I2C status.
> +        */
> +       if (ack) {
> +               i2c_dev->err = -EIO;
> +               sprd_i2c_dump_reg(i2c_dev);
> +       } else if (msg->flags & I2C_M_RD && i2c_dev->count) {
> +               sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, i2c_dev->count);
> +       }
> +
> +       /* Transmission is done and clear ack and start operation */
> +       sprd_i2c_clear_ack(i2c_dev);
> +       sprd_i2c_clear_start(i2c_dev);
> +       complete(&i2c_dev->complete);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t sprd_i2c_isr(int irq, void *dev_id)
> +{
> +       struct sprd_i2c *i2c_dev = dev_id;
> +       struct i2c_msg *msg = i2c_dev->msg;
> +       u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
> +       int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
> +       u32 i2c_tran;
> +
> +       if (msg->flags & I2C_M_RD)
> +               i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
> +       else
> +               i2c_tran = i2c_count;
> +
> +       /*
> +        * If ack == 0 means we got one ACK, if ack != 0 means we did not
> +        * get one ACK from slave when writing data, then we should finish
> +        * this transmission since we got some errors.
> +        *
> +        * When writing data, if i2c_tran == 0 which means we have writen
> +        * done all data, then we can finish this transmission.
> +        *
> +        * When reading data, if conut < rx fifo full threshold, which
> +        * means we can read all data in one time, then we can finish this
> +        * transmission too.
> +        */
> +       if (!i2c_tran || ack) {
> +               sprd_i2c_clear_start(i2c_dev);
> +               sprd_i2c_clear_irq(i2c_dev);
> +       }
> +
> +       sprd_i2c_set_fifo_empty_int(i2c_dev, 0);
> +       sprd_i2c_set_fifo_full_int(i2c_dev, 0);
> +
> +       return IRQ_WAKE_THREAD;
> +}
> +
> +static int sprd_i2c_clk_init(struct sprd_i2c *i2c_dev)
> +{
> +       struct clk *clk_i2c, *clk_parent;
> +
> +       clk_i2c = devm_clk_get(i2c_dev->dev, "i2c");
> +       if (IS_ERR(clk_i2c)) {
> +               dev_warn(i2c_dev->dev, "i2c%d can't get the i2c clock\n",
> +                        i2c_dev->adap.nr);
> +               clk_i2c = NULL;
> +       }
> +
> +       clk_parent = devm_clk_get(i2c_dev->dev, "source");
> +       if (IS_ERR(clk_parent)) {
> +               dev_warn(i2c_dev->dev, "i2c%d can't get the source clock\n",
> +                        i2c_dev->adap.nr);
> +               clk_parent = NULL;
> +       }
> +
> +       if (clk_set_parent(clk_i2c, clk_parent))
> +               i2c_dev->src_clk = clk_get_rate(clk_i2c);
> +       else
> +               i2c_dev->src_clk = 26000000;
> +
> +       dev_dbg(i2c_dev->dev, "i2c%d set source clock is %d\n",
> +               i2c_dev->adap.nr, i2c_dev->src_clk);
> +
> +       i2c_dev->clk = devm_clk_get(i2c_dev->dev, "enable");
> +       if (IS_ERR(i2c_dev->clk)) {
> +               dev_warn(i2c_dev->dev, "i2c%d can't get the enable clock\n",
> +                        i2c_dev->adap.nr);
> +               i2c_dev->clk = NULL;
> +       }
> +
> +       return 0;
> +}
> +
> +static int sprd_i2c_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct sprd_i2c *i2c_dev;
> +       struct resource *res;
> +       u32 prop;
> +       int ret;
> +
> +       pdev->id = of_alias_get_id(dev->of_node, "i2c");
> +
> +       i2c_dev = devm_kzalloc(dev, sizeof(struct sprd_i2c), GFP_KERNEL);
> +       if (!i2c_dev)
> +               return -ENOMEM;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       i2c_dev->base = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(i2c_dev->base))
> +               return PTR_ERR(i2c_dev->base);
> +
> +       i2c_dev->irq = platform_get_irq(pdev, 0);
> +       if (i2c_dev->irq < 0) {
> +               dev_err(&pdev->dev, "failed to get irq resource\n");
> +               return i2c_dev->irq;
> +       }
> +
> +       i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
> +       init_completion(&i2c_dev->complete);
> +       snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
> +                "%s", "sprd-i2c");
> +
> +       i2c_dev->bus_freq = 100000;
> +       i2c_dev->adap.owner = THIS_MODULE;
> +       i2c_dev->dev = dev;
> +       i2c_dev->adap.retries = 3;
> +       i2c_dev->adap.algo = &sprd_i2c_algo;
> +       i2c_dev->adap.algo_data = i2c_dev;
> +       i2c_dev->adap.dev.parent = dev;
> +       i2c_dev->adap.nr = pdev->id;
> +       i2c_dev->adap.dev.of_node = dev->of_node;
> +
> +       if (!of_property_read_u32(dev->of_node, "clock-frequency", &prop))
> +               i2c_dev->bus_freq = prop;
> +
> +       /* We only support 100k and 400k now, otherwise will return error. */
> +       if (i2c_dev->bus_freq != 100000 && i2c_dev->bus_freq != 400000)
> +               return -EINVAL;
> +
> +       sprd_i2c_clk_init(i2c_dev);
> +       platform_set_drvdata(pdev, i2c_dev);
> +
> +       ret = clk_prepare_enable(i2c_dev->clk);
> +       if (ret)
> +               return ret;
> +
> +       sprd_i2c_enable(i2c_dev);
> +
> +       pm_runtime_set_autosuspend_delay(i2c_dev->dev, SPRD_I2C_PM_TIMEOUT);
> +       pm_runtime_use_autosuspend(i2c_dev->dev);
> +       pm_runtime_set_active(i2c_dev->dev);
> +       pm_runtime_enable(i2c_dev->dev);
> +
> +       ret = pm_runtime_get_sync(i2c_dev->dev);
> +       if (ret < 0) {
> +               dev_err(&pdev->dev, "i2c%d pm runtime resume failed!\n",
> +                       pdev->id);
> +               goto err_rpm_put;
> +       }
> +
> +       ret = devm_request_threaded_irq(dev, i2c_dev->irq,
> +               sprd_i2c_isr, sprd_i2c_isr_thread,
> +               IRQF_NO_SUSPEND | IRQF_ONESHOT,
> +               pdev->name, i2c_dev);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to request irq %d\n", i2c_dev->irq);
> +               goto err_rpm_put;
> +       }
> +
> +       ret = i2c_add_numbered_adapter(&i2c_dev->adap);
> +       if (ret) {
> +               dev_err(&pdev->dev, "add adapter failed\n");
> +               goto err_rpm_put;
> +       }
> +
> +       pm_runtime_mark_last_busy(i2c_dev->dev);
> +       pm_runtime_put_autosuspend(i2c_dev->dev);
> +       return 0;
> +
> +err_rpm_put:
> +       pm_runtime_put_noidle(i2c_dev->dev);
> +       pm_runtime_disable(i2c_dev->dev);
> +       clk_disable_unprepare(i2c_dev->clk);
> +       return ret;
> +}
> +
> +static int sprd_i2c_remove(struct platform_device *pdev)
> +{
> +       struct sprd_i2c *i2c_dev = platform_get_drvdata(pdev);
> +       int ret;
> +
> +       ret = pm_runtime_get_sync(i2c_dev->dev);
> +       if (ret < 0)
> +               return ret;
> +
> +       i2c_del_adapter(&i2c_dev->adap);
> +       clk_disable_unprepare(i2c_dev->clk);
> +
> +       pm_runtime_put_noidle(i2c_dev->dev);
> +       pm_runtime_disable(i2c_dev->dev);
> +
> +       return 0;
> +}
> +
> +static int __maybe_unused sprd_i2c_suspend_noirq(struct device *pdev)
> +{
> +       return pm_runtime_force_suspend(pdev);
> +}
> +
> +static int __maybe_unused sprd_i2c_resume_noirq(struct device *pdev)
> +{
> +       return pm_runtime_force_resume(pdev);
> +}
> +
> +static int __maybe_unused sprd_i2c_runtime_suspend(struct device *pdev)
> +{
> +       struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
> +
> +       clk_disable_unprepare(i2c_dev->clk);
> +
> +       return 0;
> +}
> +
> +static int __maybe_unused sprd_i2c_runtime_resume(struct device *pdev)
> +{
> +       struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
> +       int ret;
> +
> +       ret = clk_prepare_enable(i2c_dev->clk);
> +       if (ret)
> +               return ret;
> +
> +       sprd_i2c_enable(i2c_dev);
> +
> +       return 0;
> +}
> +
> +static const struct dev_pm_ops sprd_i2c_pm_ops = {
> +       SET_RUNTIME_PM_OPS(sprd_i2c_runtime_suspend,
> +                          sprd_i2c_runtime_resume, NULL)
> +
> +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sprd_i2c_suspend_noirq,
> +                                     sprd_i2c_resume_noirq)
> +};
> +
> +static const struct of_device_id sprd_i2c_of_match[] = {
> +       { .compatible = "sprd,sc9860-i2c", },
> +};
> +
> +static struct platform_driver sprd_i2c_driver = {
> +       .probe = sprd_i2c_probe,
> +       .remove = sprd_i2c_remove,
> +       .driver = {
> +                  .name = "sprd-i2c",
> +                  .of_match_table = sprd_i2c_of_match,
> +                  .pm = &sprd_i2c_pm_ops,
> +       },
> +};
> +
> +static int sprd_i2c_init(void)
> +{
> +       return platform_driver_register(&sprd_i2c_driver);
> +}
> +arch_initcall_sync(sprd_i2c_init);
> --
> 1.7.9.5
>

Hi Andy,

On 四,  7月 06, 2017 at 12:00:29下午 +0300, Andy Shevchenko wrote:
> On Thu, Jul 6, 2017 at 11:47 AM, Baolin Wang <baolin.wang@spreadtrum.com> wrote:
> > This patch adds the I2C controller driver for Spreadtrum SC9860 platform.
> >
> 
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> 
> P.S. There is still room for improvement, though it either requires
> additional changes to the kernel or minor on this stage. Would be done
> later.

Thanks for your reviewed tag, and I saw your patches to add writesb/readsb
on x86 platform, I will create fix patch if your patches were applied.

> 
> > Signed-off-by: Baolin Wang <baolin.wang@spreadtrum.com>
> > ---
> > Changes since v3:
> >  - Use SPDX-License-Identifier tag instead.
> >
> > Changes since v2:
> >  - Remove some redundant comments and parens.
> >  - Define macros instead of magic number.
> >  - Add some comments to explain clock formula.
> >  - Change of_clk_get_by_name() to devm_clk_get().
> >  - Deal with other frequency.
> >  - Change register definiton to low case.
> >  - Change is_last_msg to boolean.
> >  - Other optimization.
> >
> > Changes sice v1:
> >  - Power on I2C device in probe().
> >  - Remove redundant macros and usb __maybe_unused.
> >  - Remove redundant 'of_match_ptr'.
> >  - Modify return values and check the return value for 'clk_prepare_enable'.
> > ---
> >  drivers/i2c/busses/Kconfig    |    7 +
> >  drivers/i2c/busses/Makefile   |    1 +
> >  drivers/i2c/busses/i2c-sprd.c |  676 +++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 684 insertions(+)
> >  create mode 100644 drivers/i2c/busses/i2c-sprd.c
> >
> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> > index 8adc0f1..86476b9 100644
> > --- a/drivers/i2c/busses/Kconfig
> > +++ b/drivers/i2c/busses/Kconfig
> > @@ -877,6 +877,13 @@ config I2C_SIRF
> >           This driver can also be built as a module.  If so, the module
> >           will be called i2c-sirf.
> >
> > +config I2C_SPRD
> > +       bool "Spreadtrum I2C interface"
> > +       depends on ARCH_SPRD
> > +       help
> > +         If you say yes to this option, support will be included for the
> > +         Spreadtrum I2C interface.
> > +
> >  config I2C_ST
> >         tristate "STMicroelectronics SSC I2C support"
> >         depends on ARCH_STI
> > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> > index 30b6085..dd46c21 100644
> > --- a/drivers/i2c/busses/Makefile
> > +++ b/drivers/i2c/busses/Makefile
> > @@ -84,6 +84,7 @@ obj-$(CONFIG_I2C_SH7760)      += i2c-sh7760.o
> >  obj-$(CONFIG_I2C_SH_MOBILE)    += i2c-sh_mobile.o
> >  obj-$(CONFIG_I2C_SIMTEC)       += i2c-simtec.o
> >  obj-$(CONFIG_I2C_SIRF)         += i2c-sirf.o
> > +obj-$(CONFIG_I2C_SPRD)         += i2c-sprd.o
> >  obj-$(CONFIG_I2C_ST)           += i2c-st.o
> >  obj-$(CONFIG_I2C_STM32F4)      += i2c-stm32f4.o
> >  obj-$(CONFIG_I2C_STU300)       += i2c-stu300.o
> > diff --git a/drivers/i2c/busses/i2c-sprd.c b/drivers/i2c/busses/i2c-sprd.c
> > new file mode 100644
> > index 0000000..4193f4d
> > --- /dev/null
> > +++ b/drivers/i2c/busses/i2c-sprd.c
> > @@ -0,0 +1,676 @@
> > +/*
> > + * Copyright (C) 2017 Spreadtrum Communications Inc.
> > + *
> > + * SPDX-License-Identifier: (GPL-2.0+ OR MIT)
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/io.h>
> > +#include <linux/i2c.h>
> > +#include <linux/init.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/kernel.h>
> > +#include <linux/of.h>
> > +#include <linux/of_device.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/pm_runtime.h>
> > +
> > +#define I2C_CTL                        0x00
> > +#define I2C_ADDR_CFG           0x04
> > +#define I2C_COUNT              0x08
> > +#define I2C_RX                 0x0c
> > +#define I2C_TX                 0x10
> > +#define I2C_STATUS             0x14
> > +#define I2C_HSMODE_CFG         0x18
> > +#define I2C_VERSION            0x1c
> > +#define ADDR_DVD0              0x20
> > +#define ADDR_DVD1              0x24
> > +#define ADDR_STA0_DVD          0x28
> > +#define ADDR_RST               0x2c
> > +
> > +/* I2C_CTL */
> > +#define STP_EN                 BIT(20)
> > +#define FIFO_AF_LVL_MASK       GENMASK(19, 16)
> > +#define FIFO_AF_LVL            16
> > +#define FIFO_AE_LVL_MASK       GENMASK(15, 12)
> > +#define FIFO_AE_LVL            12
> > +#define I2C_DMA_EN             BIT(11)
> > +#define FULL_INTEN             BIT(10)
> > +#define EMPTY_INTEN            BIT(9)
> > +#define I2C_DVD_OPT            BIT(8)
> > +#define I2C_OUT_OPT            BIT(7)
> > +#define I2C_TRIM_OPT           BIT(6)
> > +#define I2C_HS_MODE            BIT(4)
> > +#define I2C_MODE               BIT(3)
> > +#define I2C_EN                 BIT(2)
> > +#define I2C_INT_EN             BIT(1)
> > +#define I2C_START              BIT(0)
> > +
> > +/* I2C_STATUS */
> > +#define SDA_IN                 BIT(21)
> > +#define SCL_IN                 BIT(20)
> > +#define FIFO_FULL              BIT(4)
> > +#define FIFO_EMPTY             BIT(3)
> > +#define I2C_INT                        BIT(2)
> > +#define I2C_RX_ACK             BIT(1)
> > +#define I2C_BUSY               BIT(0)
> > +
> > +/* ADDR_RST */
> > +#define I2C_RST                        BIT(0)
> > +
> > +#define I2C_FIFO_DEEP          12
> > +#define I2C_FIFO_FULL_THLD     15
> > +#define I2C_FIFO_EMPTY_THLD    4
> > +#define I2C_DATA_STEP          8
> > +#define I2C_ADDR_DVD0_CALC(high, low)  \
> > +       ((((high) & GENMASK(15, 0)) << 16) | ((low) & GENMASK(15, 0)))
> > +#define I2C_ADDR_DVD1_CALC(high, low)  \
> > +       (((high) & GENMASK(31, 16)) | (((low) & GENMASK(31, 16)) >> 16))
> > +
> > +/* timeout (ms) for pm runtime autosuspend */
> > +#define SPRD_I2C_PM_TIMEOUT    1000
> > +
> > +/* SPRD i2c data structure */
> > +struct sprd_i2c {
> > +       struct i2c_adapter adap;
> > +       struct device *dev;
> > +       void __iomem *base;
> > +       struct i2c_msg *msg;
> > +       struct clk *clk;
> > +       unsigned int src_clk;
> > +       unsigned int bus_freq;
> > +       struct completion complete;
> > +       u8 *buf;
> > +       u16 count;
> > +       int irq;
> > +       int err;
> > +};
> > +
> > +static void sprd_i2c_dump_reg(struct sprd_i2c *i2c_dev)
> > +{
> > +       dev_err(&i2c_dev->adap.dev, ": ======dump i2c-%d reg=======\n",
> > +               i2c_dev->adap.nr);
> > +       dev_err(&i2c_dev->adap.dev, ": I2C_CTRL:0x%x\n",
> > +               readl(i2c_dev->base + I2C_CTL));
> > +       dev_err(&i2c_dev->adap.dev, ": I2C_ADDR_CFG:0x%x\n",
> > +               readl(i2c_dev->base + I2C_ADDR_CFG));
> > +       dev_err(&i2c_dev->adap.dev, ": I2C_COUNT:0x%x\n",
> > +               readl(i2c_dev->base + I2C_COUNT));
> > +       dev_err(&i2c_dev->adap.dev, ": I2C_RX:0x%x\n",
> > +               readl(i2c_dev->base + I2C_RX));
> > +       dev_err(&i2c_dev->adap.dev, ": I2C_STATUS:0x%x\n",
> > +               readl(i2c_dev->base + I2C_STATUS));
> > +       dev_err(&i2c_dev->adap.dev, ": ADDR_DVD0:0x%x\n",
> > +               readl(i2c_dev->base + ADDR_DVD0));
> > +       dev_err(&i2c_dev->adap.dev, ": ADDR_DVD1:0x%x\n",
> > +               readl(i2c_dev->base + ADDR_DVD1));
> > +       dev_err(&i2c_dev->adap.dev, ": ADDR_STA0_DVD:0x%x\n",
> > +               readl(i2c_dev->base + ADDR_STA0_DVD));
> > +       dev_err(&i2c_dev->adap.dev, ": ADDR_RST:0x%x\n",
> > +               readl(i2c_dev->base + ADDR_RST));
> > +}
> > +
> > +static void sprd_i2c_set_count(struct sprd_i2c *i2c_dev, u32 count)
> > +{
> > +       writel(count, i2c_dev->base + I2C_COUNT);
> > +}
> > +
> > +static void sprd_i2c_send_stop(struct sprd_i2c *i2c_dev, int stop)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       if (stop)
> > +               writel(tmp & ~STP_EN, i2c_dev->base + I2C_CTL);
> > +       else
> > +               writel(tmp | STP_EN, i2c_dev->base + I2C_CTL);
> > +}
> > +
> > +static void sprd_i2c_clear_start(struct sprd_i2c *i2c_dev)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       writel(tmp & ~I2C_START, i2c_dev->base + I2C_CTL);
> > +}
> > +
> > +static void sprd_i2c_clear_ack(struct sprd_i2c *i2c_dev)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
> > +
> > +       writel(tmp & ~I2C_RX_ACK, i2c_dev->base + I2C_STATUS);
> > +}
> > +
> > +static void sprd_i2c_clear_irq(struct sprd_i2c *i2c_dev)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_STATUS);
> > +
> > +       writel(tmp & ~I2C_INT, i2c_dev->base + I2C_STATUS);
> > +}
> > +
> > +static void sprd_i2c_reset_fifo(struct sprd_i2c *i2c_dev)
> > +{
> > +       writel(I2C_RST, i2c_dev->base + ADDR_RST);
> > +}
> > +
> > +static void sprd_i2c_set_devaddr(struct sprd_i2c *i2c_dev, struct i2c_msg *m)
> > +{
> > +       writel(m->addr << 1, i2c_dev->base + I2C_ADDR_CFG);
> > +}
> > +
> > +static void sprd_i2c_write_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u32 len)
> > +{
> > +       u32 i;
> > +
> > +       for (i = 0; i < len; i++)
> > +               writeb(buf[i], i2c_dev->base + I2C_TX);
> > +}
> > +
> > +static void sprd_i2c_read_bytes(struct sprd_i2c *i2c_dev, u8 *buf, u16 len)
> > +{
> > +       u32 i;
> > +
> > +       for (i = 0; i < len; i++)
> > +               buf[i] = readb(i2c_dev->base + I2C_RX);
> > +}
> > +
> > +static void sprd_i2c_set_full_thld(struct sprd_i2c *i2c_dev, u32 full_thld)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       tmp &= ~FIFO_AF_LVL_MASK;
> > +       tmp |= full_thld << FIFO_AF_LVL;
> > +       writel(tmp, i2c_dev->base + I2C_CTL);
> > +};
> > +
> > +static void sprd_i2c_set_empty_thld(struct sprd_i2c *i2c_dev, u32 empty_thld)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       tmp &= ~FIFO_AE_LVL_MASK;
> > +       tmp |= empty_thld << FIFO_AE_LVL;
> > +       writel(tmp, i2c_dev->base + I2C_CTL);
> > +};
> > +
> > +static void sprd_i2c_set_fifo_full_int(struct sprd_i2c *i2c_dev, int enable)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       if (enable)
> > +               tmp |= FULL_INTEN;
> > +       else
> > +               tmp &= ~FULL_INTEN;
> > +
> > +       writel(tmp, i2c_dev->base + I2C_CTL);
> > +};
> > +
> > +static void sprd_i2c_set_fifo_empty_int(struct sprd_i2c *i2c_dev, int enable)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       if (enable)
> > +               tmp |= EMPTY_INTEN;
> > +       else
> > +               tmp &= ~EMPTY_INTEN;
> > +
> > +       writel(tmp, i2c_dev->base + I2C_CTL);
> > +};
> > +
> > +static void sprd_i2c_opt_start(struct sprd_i2c *i2c_dev)
> > +{
> > +       unsigned int tmp = readl(i2c_dev->base + I2C_CTL);
> > +
> > +       writel(tmp | I2C_START, i2c_dev->base + I2C_CTL);
> > +}
> > +
> > +static void sprd_i2c_opt_mode(struct sprd_i2c *i2c_dev, int rw)
> > +{
> > +       unsigned int cmd = readl(i2c_dev->base + I2C_CTL) & ~I2C_MODE;
> > +
> > +       writel(cmd | rw << 3, i2c_dev->base + I2C_CTL);
> > +}
> > +
> > +static void sprd_i2c_data_transfer(struct sprd_i2c *i2c_dev)
> > +{
> > +       u32 i2c_count = i2c_dev->count;
> > +       u32 need_tran = i2c_count <= I2C_FIFO_DEEP ? i2c_count : I2C_FIFO_DEEP;
> > +       struct i2c_msg *msg = i2c_dev->msg;
> > +
> > +       if (msg->flags & I2C_M_RD) {
> > +               sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, I2C_FIFO_FULL_THLD);
> > +               i2c_dev->count -= I2C_FIFO_FULL_THLD;
> > +               i2c_dev->buf += I2C_FIFO_FULL_THLD;
> > +
> > +               /*
> > +                * If the read data count is larger than rx fifo full threshold,
> > +                * we should enable the rx fifo full interrupt to read data
> > +                * again.
> > +                */
> > +               if (i2c_dev->count >= I2C_FIFO_FULL_THLD)
> > +                       sprd_i2c_set_fifo_full_int(i2c_dev, 1);
> > +       } else {
> > +               sprd_i2c_write_bytes(i2c_dev, i2c_dev->buf, need_tran);
> > +               i2c_dev->buf += need_tran;
> > +               i2c_dev->count -= need_tran;
> > +
> > +               /*
> > +                * If the write data count is arger than tx fifo depth which
> > +                * means we can not write all data in one time, then we should
> > +                * enable the tx fifo empty interrupt to write again.
> > +                */
> > +               if (i2c_count > I2C_FIFO_DEEP)
> > +                       sprd_i2c_set_fifo_empty_int(i2c_dev, 1);
> > +       }
> > +}
> > +
> > +static int sprd_i2c_handle_msg(struct i2c_adapter *i2c_adap,
> > +                              struct i2c_msg *msg, bool is_last_msg)
> > +{
> > +       struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
> > +
> > +       i2c_dev->msg = msg;
> > +       i2c_dev->buf = msg->buf;
> > +       i2c_dev->count = msg->len;
> > +
> > +       reinit_completion(&i2c_dev->complete);
> > +       sprd_i2c_reset_fifo(i2c_dev);
> > +       sprd_i2c_set_devaddr(i2c_dev, msg);
> > +       sprd_i2c_set_count(i2c_dev, msg->len);
> > +
> > +       if ((msg->flags & I2C_M_RD)) {
> > +               sprd_i2c_opt_mode(i2c_dev, 1);
> > +               sprd_i2c_send_stop(i2c_dev, 1);
> > +       } else {
> > +               sprd_i2c_opt_mode(i2c_dev, 0);
> > +               sprd_i2c_send_stop(i2c_dev, !!is_last_msg);
> > +       }
> > +
> > +       /*
> > +        * We should enable rx fifo full interrupt to get data when receiving
> > +        * full data.
> > +        */
> > +       if ((msg->flags & I2C_M_RD))
> > +               sprd_i2c_set_fifo_full_int(i2c_dev, 1);
> > +       else
> > +               sprd_i2c_data_transfer(i2c_dev);
> > +
> > +       sprd_i2c_opt_start(i2c_dev);
> > +
> > +       wait_for_completion(&i2c_dev->complete);
> > +
> > +       return i2c_dev->err;
> > +}
> > +
> > +static int sprd_i2c_master_xfer(struct i2c_adapter *i2c_adap,
> > +                               struct i2c_msg *msgs, int num)
> > +{
> > +       struct sprd_i2c *i2c_dev = i2c_adap->algo_data;
> > +       int im, ret;
> > +
> > +       ret = pm_runtime_get_sync(i2c_dev->dev);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       for (im = 0; im < num - 1; im++) {
> > +               ret = sprd_i2c_handle_msg(i2c_adap, &msgs[im], 0);
> > +               if (ret)
> > +                       goto err_msg;
> > +       }
> > +
> > +       ret = sprd_i2c_handle_msg(i2c_adap, &msgs[im++], 1);
> > +
> > +err_msg:
> > +       pm_runtime_mark_last_busy(i2c_dev->dev);
> > +       pm_runtime_put_autosuspend(i2c_dev->dev);
> > +
> > +       return ret < 0 ? ret : im;
> > +}
> > +
> > +static u32 sprd_i2c_func(struct i2c_adapter *adap)
> > +{
> > +       return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> > +}
> > +
> > +static const struct i2c_algorithm sprd_i2c_algo = {
> > +       .master_xfer = sprd_i2c_master_xfer,
> > +       .functionality = sprd_i2c_func,
> > +};
> > +
> > +static void sprd_i2c_set_clk(struct sprd_i2c *i2c_dev, unsigned int freq)
> > +{
> > +       u32 apb_clk = i2c_dev->src_clk;
> > +       /*
> > +        * From I2C databook, the prescale calculation formula:
> > +        * prescale = freq_i2c / (4 * freq_scl) - 1;
> > +        */
> > +       u32 i2c_dvd = apb_clk / (4 * freq) - 1;
> > +       /*
> > +        * From I2C databook, the high period of SCL clock is recommended as
> > +        * 40% (2/5), and the low period of SCL clock is recommended as 60%
> > +        * (3/5), then the formula should be:
> > +        * high = (prescale * 2 * 2) / 5
> > +        * low = (prescale * 2 * 3) / 5
> > +        */
> > +       u32 high = ((i2c_dvd << 1) * 2) / 5;
> > +       u32 low = ((i2c_dvd << 1) * 3) / 5;
> > +       u32 div0 = I2C_ADDR_DVD0_CALC(high, low);
> > +       u32 div1 = I2C_ADDR_DVD1_CALC(high, low);
> > +
> > +       writel(div0, i2c_dev->base + ADDR_DVD0);
> > +       writel(div1, i2c_dev->base + ADDR_DVD1);
> > +
> > +       /* Start hold timing = hold time(us) * source clock */
> > +       if (freq == 400000)
> > +               writel((6 * apb_clk) / 10000000, i2c_dev->base + ADDR_STA0_DVD);
> > +       else if (freq == 100000)
> > +               writel((4 * apb_clk) / 1000000, i2c_dev->base + ADDR_STA0_DVD);
> > +}
> > +
> > +static void sprd_i2c_enable(struct sprd_i2c *i2c_dev)
> > +{
> > +       unsigned int tmp = I2C_DVD_OPT;
> > +
> > +       writel(tmp, i2c_dev->base + I2C_CTL);
> > +
> > +       sprd_i2c_set_full_thld(i2c_dev, I2C_FIFO_FULL_THLD);
> > +       sprd_i2c_set_empty_thld(i2c_dev, I2C_FIFO_EMPTY_THLD);
> > +
> > +       sprd_i2c_set_clk(i2c_dev, i2c_dev->bus_freq);
> > +       sprd_i2c_reset_fifo(i2c_dev);
> > +       sprd_i2c_clear_irq(i2c_dev);
> > +
> > +       tmp = readl(i2c_dev->base + I2C_CTL);
> > +       writel(tmp | I2C_EN | I2C_INT_EN, i2c_dev->base + I2C_CTL);
> > +}
> > +
> > +static irqreturn_t sprd_i2c_isr_thread(int irq, void *dev_id)
> > +{
> > +       struct sprd_i2c *i2c_dev = dev_id;
> > +       struct i2c_msg *msg = i2c_dev->msg;
> > +       int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
> > +       u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
> > +       u32 i2c_tran;
> > +
> > +       if (msg->flags & I2C_M_RD)
> > +               i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
> > +       else
> > +               i2c_tran = i2c_count;
> > +
> > +       /*
> > +        * If we got one ACK from slave when writing data, and we did not
> > +        * finish this transmission (i2c_tran is not zero), then we should
> > +        * continue to write data.
> > +        *
> > +        * For reading data, ack is always 0, if i2c_tran is not 0 which
> > +        * means we still need to contine to read data from slave.
> > +        */
> > +       if (i2c_tran && !ack) {
> > +               sprd_i2c_data_transfer(i2c_dev);
> > +               return IRQ_HANDLED;
> > +       }
> > +
> > +       i2c_dev->err = 0;
> > +
> > +       /*
> > +        * If we did not get one ACK from slave when writing data, we should
> > +        * dump all registers to check I2C status.
> > +        */
> > +       if (ack) {
> > +               i2c_dev->err = -EIO;
> > +               sprd_i2c_dump_reg(i2c_dev);
> > +       } else if (msg->flags & I2C_M_RD && i2c_dev->count) {
> > +               sprd_i2c_read_bytes(i2c_dev, i2c_dev->buf, i2c_dev->count);
> > +       }
> > +
> > +       /* Transmission is done and clear ack and start operation */
> > +       sprd_i2c_clear_ack(i2c_dev);
> > +       sprd_i2c_clear_start(i2c_dev);
> > +       complete(&i2c_dev->complete);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static irqreturn_t sprd_i2c_isr(int irq, void *dev_id)
> > +{
> > +       struct sprd_i2c *i2c_dev = dev_id;
> > +       struct i2c_msg *msg = i2c_dev->msg;
> > +       u32 i2c_count = readl(i2c_dev->base + I2C_COUNT);
> > +       int ack = readl(i2c_dev->base + I2C_STATUS) & I2C_RX_ACK;
> > +       u32 i2c_tran;
> > +
> > +       if (msg->flags & I2C_M_RD)
> > +               i2c_tran = i2c_dev->count >= I2C_FIFO_FULL_THLD;
> > +       else
> > +               i2c_tran = i2c_count;
> > +
> > +       /*
> > +        * If ack == 0 means we got one ACK, if ack != 0 means we did not
> > +        * get one ACK from slave when writing data, then we should finish
> > +        * this transmission since we got some errors.
> > +        *
> > +        * When writing data, if i2c_tran == 0 which means we have writen
> > +        * done all data, then we can finish this transmission.
> > +        *
> > +        * When reading data, if conut < rx fifo full threshold, which
> > +        * means we can read all data in one time, then we can finish this
> > +        * transmission too.
> > +        */
> > +       if (!i2c_tran || ack) {
> > +               sprd_i2c_clear_start(i2c_dev);
> > +               sprd_i2c_clear_irq(i2c_dev);
> > +       }
> > +
> > +       sprd_i2c_set_fifo_empty_int(i2c_dev, 0);
> > +       sprd_i2c_set_fifo_full_int(i2c_dev, 0);
> > +
> > +       return IRQ_WAKE_THREAD;
> > +}
> > +
> > +static int sprd_i2c_clk_init(struct sprd_i2c *i2c_dev)
> > +{
> > +       struct clk *clk_i2c, *clk_parent;
> > +
> > +       clk_i2c = devm_clk_get(i2c_dev->dev, "i2c");
> > +       if (IS_ERR(clk_i2c)) {
> > +               dev_warn(i2c_dev->dev, "i2c%d can't get the i2c clock\n",
> > +                        i2c_dev->adap.nr);
> > +               clk_i2c = NULL;
> > +       }
> > +
> > +       clk_parent = devm_clk_get(i2c_dev->dev, "source");
> > +       if (IS_ERR(clk_parent)) {
> > +               dev_warn(i2c_dev->dev, "i2c%d can't get the source clock\n",
> > +                        i2c_dev->adap.nr);
> > +               clk_parent = NULL;
> > +       }
> > +
> > +       if (clk_set_parent(clk_i2c, clk_parent))
> > +               i2c_dev->src_clk = clk_get_rate(clk_i2c);
> > +       else
> > +               i2c_dev->src_clk = 26000000;
> > +
> > +       dev_dbg(i2c_dev->dev, "i2c%d set source clock is %d\n",
> > +               i2c_dev->adap.nr, i2c_dev->src_clk);
> > +
> > +       i2c_dev->clk = devm_clk_get(i2c_dev->dev, "enable");
> > +       if (IS_ERR(i2c_dev->clk)) {
> > +               dev_warn(i2c_dev->dev, "i2c%d can't get the enable clock\n",
> > +                        i2c_dev->adap.nr);
> > +               i2c_dev->clk = NULL;
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +static int sprd_i2c_probe(struct platform_device *pdev)
> > +{
> > +       struct device *dev = &pdev->dev;
> > +       struct sprd_i2c *i2c_dev;
> > +       struct resource *res;
> > +       u32 prop;
> > +       int ret;
> > +
> > +       pdev->id = of_alias_get_id(dev->of_node, "i2c");
> > +
> > +       i2c_dev = devm_kzalloc(dev, sizeof(struct sprd_i2c), GFP_KERNEL);
> > +       if (!i2c_dev)
> > +               return -ENOMEM;
> > +
> > +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > +       i2c_dev->base = devm_ioremap_resource(dev, res);
> > +       if (IS_ERR(i2c_dev->base))
> > +               return PTR_ERR(i2c_dev->base);
> > +
> > +       i2c_dev->irq = platform_get_irq(pdev, 0);
> > +       if (i2c_dev->irq < 0) {
> > +               dev_err(&pdev->dev, "failed to get irq resource\n");
> > +               return i2c_dev->irq;
> > +       }
> > +
> > +       i2c_set_adapdata(&i2c_dev->adap, i2c_dev);
> > +       init_completion(&i2c_dev->complete);
> > +       snprintf(i2c_dev->adap.name, sizeof(i2c_dev->adap.name),
> > +                "%s", "sprd-i2c");
> > +
> > +       i2c_dev->bus_freq = 100000;
> > +       i2c_dev->adap.owner = THIS_MODULE;
> > +       i2c_dev->dev = dev;
> > +       i2c_dev->adap.retries = 3;
> > +       i2c_dev->adap.algo = &sprd_i2c_algo;
> > +       i2c_dev->adap.algo_data = i2c_dev;
> > +       i2c_dev->adap.dev.parent = dev;
> > +       i2c_dev->adap.nr = pdev->id;
> > +       i2c_dev->adap.dev.of_node = dev->of_node;
> > +
> > +       if (!of_property_read_u32(dev->of_node, "clock-frequency", &prop))
> > +               i2c_dev->bus_freq = prop;
> > +
> > +       /* We only support 100k and 400k now, otherwise will return error. */
> > +       if (i2c_dev->bus_freq != 100000 && i2c_dev->bus_freq != 400000)
> > +               return -EINVAL;
> > +
> > +       sprd_i2c_clk_init(i2c_dev);
> > +       platform_set_drvdata(pdev, i2c_dev);
> > +
> > +       ret = clk_prepare_enable(i2c_dev->clk);
> > +       if (ret)
> > +               return ret;
> > +
> > +       sprd_i2c_enable(i2c_dev);
> > +
> > +       pm_runtime_set_autosuspend_delay(i2c_dev->dev, SPRD_I2C_PM_TIMEOUT);
> > +       pm_runtime_use_autosuspend(i2c_dev->dev);
> > +       pm_runtime_set_active(i2c_dev->dev);
> > +       pm_runtime_enable(i2c_dev->dev);
> > +
> > +       ret = pm_runtime_get_sync(i2c_dev->dev);
> > +       if (ret < 0) {
> > +               dev_err(&pdev->dev, "i2c%d pm runtime resume failed!\n",
> > +                       pdev->id);
> > +               goto err_rpm_put;
> > +       }
> > +
> > +       ret = devm_request_threaded_irq(dev, i2c_dev->irq,
> > +               sprd_i2c_isr, sprd_i2c_isr_thread,
> > +               IRQF_NO_SUSPEND | IRQF_ONESHOT,
> > +               pdev->name, i2c_dev);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failed to request irq %d\n", i2c_dev->irq);
> > +               goto err_rpm_put;
> > +       }
> > +
> > +       ret = i2c_add_numbered_adapter(&i2c_dev->adap);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "add adapter failed\n");
> > +               goto err_rpm_put;
> > +       }
> > +
> > +       pm_runtime_mark_last_busy(i2c_dev->dev);
> > +       pm_runtime_put_autosuspend(i2c_dev->dev);
> > +       return 0;
> > +
> > +err_rpm_put:
> > +       pm_runtime_put_noidle(i2c_dev->dev);
> > +       pm_runtime_disable(i2c_dev->dev);
> > +       clk_disable_unprepare(i2c_dev->clk);
> > +       return ret;
> > +}
> > +
> > +static int sprd_i2c_remove(struct platform_device *pdev)
> > +{
> > +       struct sprd_i2c *i2c_dev = platform_get_drvdata(pdev);
> > +       int ret;
> > +
> > +       ret = pm_runtime_get_sync(i2c_dev->dev);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       i2c_del_adapter(&i2c_dev->adap);
> > +       clk_disable_unprepare(i2c_dev->clk);
> > +
> > +       pm_runtime_put_noidle(i2c_dev->dev);
> > +       pm_runtime_disable(i2c_dev->dev);
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused sprd_i2c_suspend_noirq(struct device *pdev)
> > +{
> > +       return pm_runtime_force_suspend(pdev);
> > +}
> > +
> > +static int __maybe_unused sprd_i2c_resume_noirq(struct device *pdev)
> > +{
> > +       return pm_runtime_force_resume(pdev);
> > +}
> > +
> > +static int __maybe_unused sprd_i2c_runtime_suspend(struct device *pdev)
> > +{
> > +       struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
> > +
> > +       clk_disable_unprepare(i2c_dev->clk);
> > +
> > +       return 0;
> > +}
> > +
> > +static int __maybe_unused sprd_i2c_runtime_resume(struct device *pdev)
> > +{
> > +       struct sprd_i2c *i2c_dev = dev_get_drvdata(pdev);
> > +       int ret;
> > +
> > +       ret = clk_prepare_enable(i2c_dev->clk);
> > +       if (ret)
> > +               return ret;
> > +
> > +       sprd_i2c_enable(i2c_dev);
> > +
> > +       return 0;
> > +}
> > +
> > +static const struct dev_pm_ops sprd_i2c_pm_ops = {
> > +       SET_RUNTIME_PM_OPS(sprd_i2c_runtime_suspend,
> > +                          sprd_i2c_runtime_resume, NULL)
> > +
> > +       SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(sprd_i2c_suspend_noirq,
> > +                                     sprd_i2c_resume_noirq)
> > +};
> > +
> > +static const struct of_device_id sprd_i2c_of_match[] = {
> > +       { .compatible = "sprd,sc9860-i2c", },
> > +};
> > +
> > +static struct platform_driver sprd_i2c_driver = {
> > +       .probe = sprd_i2c_probe,
> > +       .remove = sprd_i2c_remove,
> > +       .driver = {
> > +                  .name = "sprd-i2c",
> > +                  .of_match_table = sprd_i2c_of_match,
> > +                  .pm = &sprd_i2c_pm_ops,
> > +       },
> > +};
> > +
> > +static int sprd_i2c_init(void)
> > +{
> > +       return platform_driver_register(&sprd_i2c_driver);
> > +}
> > +arch_initcall_sync(sprd_i2c_init);
> > --
> > 1.7.9.5
> >
> 
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko

Hi Wolfram,

On 四,  7月 06, 2017 at 05:10:21下午 +0800, Baolin Wang wrote:
> Hi Andy,
> 
> On 四,  7月 06, 2017 at 12:00:29下午 +0300, Andy Shevchenko wrote:
> > On Thu, Jul 6, 2017 at 11:47 AM, Baolin Wang <baolin.wang@spreadtrum.com> wrote:
> > > This patch adds the I2C controller driver for Spreadtrum SC9860 platform.
> > >
> > 
> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Could you apply this patchset if there are no other comments? Do I need
resend this patch with adding Andy's reviewed tag? Thanks.