summaryrefslogtreecommitdiff
path: root/drivers/i2c/i2c-core-base.c
diff options
context:
space:
mode:
authorCodrin Ciubotariu <codrin.ciubotariu@microchip.com>2020-08-04 12:59:24 +0300
committerWolfram Sang <wsa@kernel.org>2020-08-05 12:52:27 +0300
commit75820314de26b00aaea0d0e79269c0d17914c5c4 (patch)
tree95465e05785b86ace95b5dc94cec2c43ee92db24 /drivers/i2c/i2c-core-base.c
parentdb36e827d8762eaa6aacd2c918a55ac487aa2501 (diff)
downloadlinux-75820314de26b00aaea0d0e79269c0d17914c5c4.tar.xz
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/i2c/i2c-core-base.c')
-rw-r--r--drivers/i2c/i2c-core-base.c126
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;