diff options
author | Codrin Ciubotariu <codrin.ciubotariu@microchip.com> | 2020-08-04 11:59:24 +0200 |
---|---|---|
committer | Wolfram Sang <wsa@kernel.org> | 2020-08-05 11:52:27 +0200 |
commit | 75820314de26b00aaea0d0e79269c0d17914c5c4 (patch) | |
tree | 95465e05785b86ace95b5dc94cec2c43ee92db24 /drivers | |
parent | dt-bindings: i2c: add generic properties for GPIO bus recovery (diff) | |
download | linux-75820314de26b00aaea0d0e79269c0d17914c5c4.tar.xz linux-75820314de26b00aaea0d0e79269c0d17914c5c4.zip |
i2c: core: add generic I2C GPIO recovery
Multiple I2C bus drivers use similar bindings to obtain information needed
for I2C recovery. For example, for platforms using device-tree, the
properties look something like this:
&i2c {
...
pinctrl-names = "default", "gpio";
pinctrl-0 = <&pinctrl_i2c_default>;
pinctrl-1 = <&pinctrl_i2c_gpio>;
sda-gpios = <&pio 0 GPIO_ACTIVE_HIGH>;
scl-gpios = <&pio 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
...
}
For this reason, we can add this common initialization in the core. This
way, other I2C bus drivers will be able to support GPIO recovery just by
providing a pointer to platform's pinctrl and calling i2c_recover_bus()
when SDA is stuck low.
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
[wsa: inverted one logic for better readability, minor update to kdoc]
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/i2c/i2c-core-base.c | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c index 69217d2193da..ece25560eae4 100644 --- a/drivers/i2c/i2c-core-base.c +++ b/drivers/i2c/i2c-core-base.c @@ -32,6 +32,7 @@ #include <linux/of_device.h> #include <linux/of.h> #include <linux/of_irq.h> +#include <linux/pinctrl/consumer.h> #include <linux/pm_domain.h> #include <linux/pm_runtime.h> #include <linux/pm_wakeirq.h> @@ -181,6 +182,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap) if (bri->prepare_recovery) bri->prepare_recovery(adap); + if (bri->pinctrl) + pinctrl_select_state(bri->pinctrl, bri->pins_gpio); /* * If we can set SDA, we will always create a STOP to ensure additional @@ -236,6 +239,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap) if (bri->unprepare_recovery) bri->unprepare_recovery(adap); + if (bri->pinctrl) + pinctrl_select_state(bri->pinctrl, bri->pins_default); return ret; } @@ -251,6 +256,125 @@ int i2c_recover_bus(struct i2c_adapter *adap) } EXPORT_SYMBOL_GPL(i2c_recover_bus); +static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap) +{ + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; + struct device *dev = &adap->dev; + struct pinctrl *p = bri->pinctrl; + + /* + * we can't change states without pinctrl, so remove the states if + * populated + */ + if (!p) { + bri->pins_default = NULL; + bri->pins_gpio = NULL; + return; + } + + if (!bri->pins_default) { + bri->pins_default = pinctrl_lookup_state(p, + PINCTRL_STATE_DEFAULT); + if (IS_ERR(bri->pins_default)) { + dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found for GPIO recovery\n"); + bri->pins_default = NULL; + } + } + if (!bri->pins_gpio) { + bri->pins_gpio = pinctrl_lookup_state(p, "gpio"); + if (IS_ERR(bri->pins_gpio)) + bri->pins_gpio = pinctrl_lookup_state(p, "recovery"); + + if (IS_ERR(bri->pins_gpio)) { + dev_dbg(dev, "no gpio or recovery state found for GPIO recovery\n"); + bri->pins_gpio = NULL; + } + } + + /* for pinctrl state changes, we need all the information */ + if (bri->pins_default && bri->pins_gpio) { + dev_info(dev, "using pinctrl states for GPIO recovery"); + } else { + bri->pinctrl = NULL; + bri->pins_default = NULL; + bri->pins_gpio = NULL; + } +} + +static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap) +{ + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; + struct device *dev = &adap->dev; + struct gpio_desc *gpiod; + int ret = 0; + + /* + * don't touch the recovery information if the driver is not using + * generic SCL recovery + */ + if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery) + return 0; + + /* + * pins might be taken as GPIO, so we should inform pinctrl about + * this and move the state to GPIO + */ + if (bri->pinctrl) + pinctrl_select_state(bri->pinctrl, bri->pins_gpio); + + /* + * if there is incomplete or no recovery information, see if generic + * GPIO recovery is available + */ + if (!bri->scl_gpiod) { + gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN); + if (PTR_ERR(gpiod) == -EPROBE_DEFER) { + ret = -EPROBE_DEFER; + goto cleanup_pinctrl_state; + } + if (!IS_ERR(gpiod)) { + bri->scl_gpiod = gpiod; + bri->recover_bus = i2c_generic_scl_recovery; + dev_info(dev, "using generic GPIOs for recovery\n"); + } + } + + /* SDA GPIOD line is optional, so we care about DEFER only */ + if (!bri->sda_gpiod) { + /* + * We have SCL. Pull SCL low and wait a bit so that SDA glitches + * have no effect. + */ + gpiod_direction_output(bri->scl_gpiod, 0); + udelay(10); + gpiod = devm_gpiod_get(dev, "sda", GPIOD_IN); + + /* Wait a bit in case of a SDA glitch, and then release SCL. */ + udelay(10); + gpiod_direction_output(bri->scl_gpiod, 1); + + if (PTR_ERR(gpiod) == -EPROBE_DEFER) { + ret = -EPROBE_DEFER; + goto cleanup_pinctrl_state; + } + if (!IS_ERR(gpiod)) + bri->sda_gpiod = gpiod; + } + +cleanup_pinctrl_state: + /* change the state of the pins back to their default state */ + if (bri->pinctrl) + pinctrl_select_state(bri->pinctrl, bri->pins_default); + + return ret; +} + +static int i2c_gpio_init_recovery(struct i2c_adapter *adap) +{ + i2c_gpio_init_pinctrl_recovery(adap); + return i2c_gpio_init_generic_recovery(adap); +} + static void i2c_init_recovery(struct i2c_adapter *adap) { struct i2c_bus_recovery_info *bri = adap->bus_recovery_info; @@ -259,6 +383,8 @@ static void i2c_init_recovery(struct i2c_adapter *adap) if (!bri) return; + i2c_gpio_init_recovery(adap); + if (!bri->recover_bus) { err_str = "no recover_bus() found"; goto err; |