[v5,2/2] i2c: mux: ltc4306: LTC4306 and LTC4305 I2C multiplexer/switch

Submitted by Hennerich, Michael on April 11, 2017, 12:16 p.m.

Details

Message ID 1491912976-8396-2-git-send-email-michael.hennerich@analog.com
State New
Headers show

Commit Message

Hennerich, Michael April 11, 2017, 12:16 p.m.
From: Michael Hennerich <michael.hennerich@analog.com>

This patch adds support for the Analog Devices / Linear Technology
LTC4306 and LTC4305 4/2 Channel I2C Bus Multiplexer/Switches.
The LTC4306 optionally provides two general purpose input/output pins
(GPIOs) that can be configured as logic inputs, opendrain outputs or
push-pull outputs via the generic GPIOLIB framework.

Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>

---

Changes since v1:

 - Sort makefile entries
 - Sort driver includes
 - Use proper defines
 - Miscellaneous coding style fixups
 - Rename mux select callback
 - Revise i2c-mux-idle-disconnect handling
 - Add ENABLE GPIO handling on error and device removal.
 - Remove surplus of_match_device call.

Changes since v2:

 - Stop double error reporting (i2c_mux_add_adapter)
 - Change subject
 - Split dt bindings to separate patch

Changes since v3:

 - Change subject and add spaces
 - Convert to I2C_MUX_LOCKED
 - Convert to regmap
 - Remove local register cache
 - Restore previous ENABLE GPIO handling
 - Initially pulse ENABLE low
 - Eliminate i2c client struct in driver state structure
 - Simplify error return path
 - Misc minor cleanups

Changes since v4:

 - Remove redundant includes
 - Use regmap cache type REGCACHE_FLAT
 - gpio_get restore double negates on return
 - Implement gpio_get_direction
 - Use unified device property interface
 - mux_alloc exact number of channels
 - Reword kconfig help text
---
 MAINTAINERS                         |   8 +
 drivers/i2c/muxes/Kconfig           |  11 ++
 drivers/i2c/muxes/Makefile          |   1 +
 drivers/i2c/muxes/i2c-mux-ltc4306.c | 322 ++++++++++++++++++++++++++++++++++++
 4 files changed, 342 insertions(+)
 create mode 100644 drivers/i2c/muxes/i2c-mux-ltc4306.c

Comments

Linus Walleij April 12, 2017, 8:26 a.m.
On Tue, Apr 11, 2017 at 2:16 PM,  <michael.hennerich@analog.com> wrote:

> From: Michael Hennerich <michael.hennerich@analog.com>
>
> This patch adds support for the Analog Devices / Linear Technology
> LTC4306 and LTC4305 4/2 Channel I2C Bus Multiplexer/Switches.
> The LTC4306 optionally provides two general purpose input/output pins
> (GPIOs) that can be configured as logic inputs, opendrain outputs or
> push-pull outputs via the generic GPIOLIB framework.
>
> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
(...)
> Changes since v4:

Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Please go ahead and merge to the i2c tree if you like.

Yours,
Linus Walleij
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Peter Rosin April 12, 2017, 4:53 p.m.
On 2017-04-12 10:26, Linus Walleij wrote:
> On Tue, Apr 11, 2017 at 2:16 PM,  <michael.hennerich@analog.com> wrote:
> 
>> From: Michael Hennerich <michael.hennerich@analog.com>
>>
>> This patch adds support for the Analog Devices / Linear Technology
>> LTC4306 and LTC4305 4/2 Channel I2C Bus Multiplexer/Switches.
>> The LTC4306 optionally provides two general purpose input/output pins
>> (GPIOs) that can be configured as logic inputs, opendrain outputs or
>> push-pull outputs via the generic GPIOLIB framework.

Great, thanks for your contribution Michael! Both patches pushed to the
for-next branch of the i2c-mux tree.

>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
> (...)
>> Changes since v4:
> 
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> 
> Please go ahead and merge to the i2c tree if you like.

Yup, thanks for the review! (But not merged directly to the i2c tree,
although they will get there eventually...)

Cheers,
peda

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Hennerich, Michael April 13, 2017, 6:58 a.m.
On 12.04.2017 18:53, Peter Rosin wrote:
> On 2017-04-12 10:26, Linus Walleij wrote:
>> On Tue, Apr 11, 2017 at 2:16 PM,  <michael.hennerich@analog.com> wrote:
>>
>>> From: Michael Hennerich <michael.hennerich@analog.com>
>>>
>>> This patch adds support for the Analog Devices / Linear Technology
>>> LTC4306 and LTC4305 4/2 Channel I2C Bus Multiplexer/Switches.
>>> The LTC4306 optionally provides two general purpose input/output pins
>>> (GPIOs) that can be configured as logic inputs, opendrain outputs or
>>> push-pull outputs via the generic GPIOLIB framework.
>
> Great, thanks for your contribution Michael! Both patches pushed to the
> for-next branch of the i2c-mux tree.
>
>>> Signed-off-by: Michael Hennerich <michael.hennerich@analog.com>
>> (...)
>>> Changes since v4:
>>
>> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
>>
>> Please go ahead and merge to the i2c tree if you like.
>
> Yup, thanks for the review! (But not merged directly to the i2c tree,
> although they will get there eventually...)
>
> Cheers,
> peda
>
>

Peter and Linus,

Thanks for your precious time - really appreciated!

Patch hide | download patch | download mbox

diff --git a/MAINTAINERS b/MAINTAINERS
index c776906..9a27a19 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -7698,6 +7698,14 @@  S:	Maintained
 F:	Documentation/hwmon/ltc4261
 F:	drivers/hwmon/ltc4261.c
 
+LTC4306 I2C MULTIPLEXER DRIVER
+M:	Michael Hennerich <michael.hennerich@analog.com>
+W:	http://ez.analog.com/community/linux-device-drivers
+L:	linux-i2c@vger.kernel.org
+S:	Supported
+F:	drivers/i2c/muxes/i2c-mux-ltc4306.c
+F:	Documentation/devicetree/bindings/i2c/i2c-mux-ltc4306.txt
+
 LTP (Linux Test Project)
 M:	Mike Frysinger <vapier@gentoo.org>
 M:	Cyril Hrubis <chrubis@suse.cz>
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 10b3d17..1e160fc 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -30,6 +30,17 @@  config I2C_MUX_GPIO
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-mux-gpio.
 
+config I2C_MUX_LTC4306
+	tristate "LTC LTC4306/5 I2C multiplexer"
+	select GPIOLIB
+	select REGMAP_I2C
+	help
+	  If you say yes here you get support for the Analog Devices
+	  LTC4306 or LTC4305 I2C mux/switch devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-mux-ltc4306.
+
 config I2C_MUX_PCA9541
 	tristate "NXP PCA9541 I2C Master Selector"
 	help
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 9948fa4..ff7618c 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -6,6 +6,7 @@  obj-$(CONFIG_I2C_ARB_GPIO_CHALLENGE)	+= i2c-arb-gpio-challenge.o
 obj-$(CONFIG_I2C_DEMUX_PINCTRL)		+= i2c-demux-pinctrl.o
 
 obj-$(CONFIG_I2C_MUX_GPIO)	+= i2c-mux-gpio.o
+obj-$(CONFIG_I2C_MUX_LTC4306)	+= i2c-mux-ltc4306.o
 obj-$(CONFIG_I2C_MUX_MLXCPLD)	+= i2c-mux-mlxcpld.o
 obj-$(CONFIG_I2C_MUX_PCA9541)	+= i2c-mux-pca9541.o
 obj-$(CONFIG_I2C_MUX_PCA954x)	+= i2c-mux-pca954x.o
diff --git a/drivers/i2c/muxes/i2c-mux-ltc4306.c b/drivers/i2c/muxes/i2c-mux-ltc4306.c
new file mode 100644
index 0000000..311b1cc
--- /dev/null
+++ b/drivers/i2c/muxes/i2c-mux-ltc4306.c
@@ -0,0 +1,322 @@ 
+/*
+ * Linear Technology LTC4306 and LTC4305 I2C multiplexer/switch
+ *
+ * Copyright (C) 2017 Analog Devices Inc.
+ *
+ * Licensed under the GPL-2.
+ *
+ * Based on: i2c-mux-pca954x.c
+ *
+ * Datasheet: http://cds.linear.com/docs/en/datasheet/4306.pdf
+ */
+
+#include <linux/gpio/consumer.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c-mux.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+
+#define LTC4305_MAX_NCHANS 2
+#define LTC4306_MAX_NCHANS 4
+
+#define LTC_REG_STATUS	0x0
+#define LTC_REG_CONFIG	0x1
+#define LTC_REG_MODE	0x2
+#define LTC_REG_SWITCH	0x3
+
+#define LTC_DOWNSTREAM_ACCL_EN	BIT(6)
+#define LTC_UPSTREAM_ACCL_EN	BIT(7)
+
+#define LTC_GPIO_ALL_INPUT	0xC0
+#define LTC_SWITCH_MASK		0xF0
+
+enum ltc_type {
+	ltc_4305,
+	ltc_4306,
+};
+
+struct chip_desc {
+	u8 nchans;
+	u8 num_gpios;
+};
+
+struct ltc4306 {
+	struct regmap *regmap;
+	struct gpio_chip gpiochip;
+	const struct chip_desc *chip;
+};
+
+static const struct chip_desc chips[] = {
+	[ltc_4305] = {
+		.nchans = LTC4305_MAX_NCHANS,
+	},
+	[ltc_4306] = {
+		.nchans = LTC4306_MAX_NCHANS,
+		.num_gpios = 2,
+	},
+};
+
+static bool ltc4306_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	return (reg == LTC_REG_CONFIG) ? true : false;
+}
+
+static const struct regmap_config ltc4306_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LTC_REG_SWITCH,
+	.volatile_reg = ltc4306_is_volatile_reg,
+	.cache_type = REGCACHE_FLAT,
+};
+
+static int ltc4306_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(data->regmap, LTC_REG_CONFIG, &val);
+	if (ret < 0)
+		return ret;
+
+	return !!(val & BIT(1 - offset));
+}
+
+static void ltc4306_gpio_set(struct gpio_chip *chip, unsigned int offset,
+			     int value)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	regmap_update_bits(data->regmap, LTC_REG_CONFIG, BIT(5 - offset),
+			   value ? BIT(5 - offset) : 0);
+}
+
+static int ltc4306_gpio_get_direction(struct gpio_chip *chip,
+				      unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+	int ret;
+
+	ret = regmap_read(data->regmap, LTC_REG_MODE, &val);
+	if (ret < 0)
+		return ret;
+
+	return !!(val & BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_input(struct gpio_chip *chip,
+					unsigned int offset)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(7 - offset), BIT(7 - offset));
+}
+
+static int ltc4306_gpio_direction_output(struct gpio_chip *chip,
+					 unsigned int offset, int value)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+
+	ltc4306_gpio_set(chip, offset, value);
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(7 - offset), 0);
+}
+
+static int ltc4306_gpio_set_config(struct gpio_chip *chip,
+				   unsigned int offset, unsigned long config)
+{
+	struct ltc4306 *data = gpiochip_get_data(chip);
+	unsigned int val;
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
+		val = 0;
+		break;
+	case PIN_CONFIG_DRIVE_PUSH_PULL:
+		val = BIT(4 - offset);
+		break;
+	default:
+		return -ENOTSUPP;
+	}
+
+	return regmap_update_bits(data->regmap, LTC_REG_MODE,
+				  BIT(4 - offset), val);
+}
+
+static int ltc4306_gpio_init(struct ltc4306 *data)
+{
+	struct device *dev = regmap_get_device(data->regmap);
+
+	if (!data->chip->num_gpios)
+		return 0;
+
+	data->gpiochip.label = dev_name(dev);
+	data->gpiochip.base = -1;
+	data->gpiochip.ngpio = data->chip->num_gpios;
+	data->gpiochip.parent = dev;
+	data->gpiochip.can_sleep = true;
+	data->gpiochip.get_direction = ltc4306_gpio_get_direction;
+	data->gpiochip.direction_input = ltc4306_gpio_direction_input;
+	data->gpiochip.direction_output = ltc4306_gpio_direction_output;
+	data->gpiochip.get = ltc4306_gpio_get;
+	data->gpiochip.set = ltc4306_gpio_set;
+	data->gpiochip.set_config = ltc4306_gpio_set_config;
+	data->gpiochip.owner = THIS_MODULE;
+
+	/* gpiolib assumes all GPIOs default input */
+	regmap_write(data->regmap, LTC_REG_MODE, LTC_GPIO_ALL_INPUT);
+
+	return devm_gpiochip_add_data(dev, &data->gpiochip, data);
+}
+
+static int ltc4306_select_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct ltc4306 *data = i2c_mux_priv(muxc);
+
+	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+				  LTC_SWITCH_MASK, BIT(7 - chan));
+}
+
+static int ltc4306_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
+{
+	struct ltc4306 *data = i2c_mux_priv(muxc);
+
+	return regmap_update_bits(data->regmap, LTC_REG_SWITCH,
+				  LTC_SWITCH_MASK, 0);
+}
+
+static const struct i2c_device_id ltc4306_id[] = {
+	{ "ltc4305", ltc_4305 },
+	{ "ltc4306", ltc_4306 },
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc4306_id);
+
+static const struct of_device_id ltc4306_of_match[] = {
+	{ .compatible = "lltc,ltc4305", .data = &chips[ltc_4305] },
+	{ .compatible = "lltc,ltc4306", .data = &chips[ltc_4306] },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, ltc4306_of_match);
+
+static int ltc4306_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+	const struct chip_desc *chip;
+	struct i2c_mux_core *muxc;
+	struct ltc4306 *data;
+	struct gpio_desc *gpio;
+	bool idle_disc;
+	unsigned int val = 0;
+	int num, ret;
+
+	chip = of_device_get_match_data(&client->dev);
+
+	if (!chip)
+		chip = &chips[id->driver_data];
+
+	idle_disc = device_property_read_bool(&client->dev,
+					      "i2c-mux-idle-disconnect");
+
+	muxc = i2c_mux_alloc(adap, &client->dev,
+			     chip->nchans, sizeof(*data),
+			     I2C_MUX_LOCKED, ltc4306_select_mux,
+			     idle_disc ? ltc4306_deselect_mux : NULL);
+	if (!muxc)
+		return -ENOMEM;
+	data = i2c_mux_priv(muxc);
+	data->chip = chip;
+
+	i2c_set_clientdata(client, muxc);
+
+	data->regmap = devm_regmap_init_i2c(client, &ltc4306_regmap_config);
+	if (IS_ERR(data->regmap)) {
+		ret = PTR_ERR(data->regmap);
+		dev_err(&client->dev, "Failed to allocate register map: %d\n",
+			ret);
+		return ret;
+	}
+
+	/* Reset and enable the mux if an enable GPIO is specified. */
+	gpio = devm_gpiod_get_optional(&client->dev, "enable", GPIOD_OUT_LOW);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+
+	if (gpio) {
+		udelay(1);
+		gpiod_set_value(gpio, 1);
+	}
+
+	/*
+	 * Write the mux register at addr to verify
+	 * that the mux is in fact present. This also
+	 * initializes the mux to disconnected state.
+	 */
+	if (regmap_write(data->regmap, LTC_REG_SWITCH, 0) < 0) {
+		dev_warn(&client->dev, "probe failed\n");
+		return -ENODEV;
+	}
+
+	if (device_property_read_bool(&client->dev,
+				      "ltc,downstream-accelerators-enable"))
+		val |= LTC_DOWNSTREAM_ACCL_EN;
+
+	if (device_property_read_bool(&client->dev,
+				      "ltc,upstream-accelerators-enable"))
+		val |= LTC_UPSTREAM_ACCL_EN;
+
+	if (regmap_write(data->regmap, LTC_REG_CONFIG, val) < 0)
+		return -ENODEV;
+
+	ret = ltc4306_gpio_init(data);
+	if (ret < 0)
+		return ret;
+
+	/* Now create an adapter for each channel */
+	for (num = 0; num < chip->nchans; num++) {
+		ret = i2c_mux_add_adapter(muxc, 0, num, 0);
+		if (ret) {
+			i2c_mux_del_adapters(muxc);
+			return ret;
+		}
+	}
+
+	dev_info(&client->dev,
+		 "registered %d multiplexed busses for I2C switch %s\n",
+		 num, client->name);
+
+	return 0;
+}
+
+static int ltc4306_remove(struct i2c_client *client)
+{
+	struct i2c_mux_core *muxc = i2c_get_clientdata(client);
+
+	i2c_mux_del_adapters(muxc);
+
+	return 0;
+}
+
+static struct i2c_driver ltc4306_driver = {
+	.driver		= {
+		.name	= "ltc4306",
+		.of_match_table = of_match_ptr(ltc4306_of_match),
+	},
+	.probe		= ltc4306_probe,
+	.remove		= ltc4306_remove,
+	.id_table	= ltc4306_id,
+};
+
+module_i2c_driver(ltc4306_driver);
+
+MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
+MODULE_DESCRIPTION("Linear Technology LTC4306, LTC4305 I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");