drivers: i2c: add bus recovery

Added bus recovery support for ambiq i2c

Signed-off-by: Hao Luo <hluo@ambiq.com>

boards/ambiq/apollo3_evb/apollo3_evb.dts

@@ -116,6 +116,8 @@
 	pinctrl-0 = <&i2c3_default>;
 	pinctrl-names = "default";
 	clock-frequency = <I2C_BITRATE_STANDARD>;
+	scl-gpios = <&gpio32_63 10 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
+	sda-gpios = <&gpio32_63 11 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
 	status = "okay";
 };
 

boards/ambiq/apollo3p_evb/apollo3p_evb.dts

@@ -116,6 +116,8 @@
 	pinctrl-0 = <&i2c3_default>;
 	pinctrl-names = "default";
 	clock-frequency = <I2C_BITRATE_STANDARD>;
+	scl-gpios = <&gpio32_63 10 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
+	sda-gpios = <&gpio32_63 11 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
 	status = "okay";
 };
 

boards/ambiq/apollo4p_blue_kxr_evb/apollo4p_blue_kxr_evb.dts

@@ -76,6 +76,8 @@
 	pinctrl-0 = <&i2c0_default>;
 	pinctrl-names = "default";
 	clock-frequency = <I2C_BITRATE_STANDARD>;
+	scl-gpios = <&gpio0_31 5 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
+	sda-gpios = <&gpio0_31 6 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
 	status = "okay";
 };
 

boards/ambiq/apollo4p_evb/apollo4p_evb.dts

@@ -88,6 +88,8 @@ compatible = "ambiq,adc";
 	pinctrl-0 = <&i2c0_default>;
 	pinctrl-names = "default";
 	clock-frequency = <I2C_BITRATE_STANDARD>;
+	scl-gpios = <&gpio0_31 5 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
+	sda-gpios = <&gpio0_31 6 (GPIO_OPEN_DRAIN | GPIO_PULL_UP)>;
 	status = "okay";
 };
 

drivers/gpio/gpio_ambiq.c

@@ -55,6 +55,11 @@ static int ambiq_gpio_pin_configure(const struct device *dev, gpio_pin_t pin, gp
 		if (flags & GPIO_SINGLE_ENDED) {
 			if (flags & GPIO_LINE_OPEN_DRAIN) {
 				pincfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_OPENDRAIN;
+				if (flags & GPIO_PULL_UP) {
+					pincfg.ePullup = AM_HAL_GPIO_PIN_PULLUP_1_5K;
+				} else if (flags & GPIO_PULL_DOWN) {
+					pincfg.ePullup = AM_HAL_GPIO_PIN_PULLDOWN;
+				}
 			}
 		} else {
 			pincfg.eGPOutcfg = AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
@@ -89,6 +94,11 @@ static int ambiq_gpio_pin_configure(const struct device *dev, gpio_pin_t pin, gp
 		if (flags & GPIO_SINGLE_ENDED) {
 			if (flags & GPIO_LINE_OPEN_DRAIN) {
 				pincfg.GP.cfg_b.eGPOutCfg = AM_HAL_GPIO_PIN_OUTCFG_OPENDRAIN;
+				if (flags & GPIO_PULL_UP) {
+					pincfg.GP.cfg_b.ePullup = AM_HAL_GPIO_PIN_PULLUP_50K;
+				} else if (flags & GPIO_PULL_DOWN) {
+					pincfg.GP.cfg_b.ePullup = AM_HAL_GPIO_PIN_PULLDOWN_50K;
+				}
 			}
 		} else {
 			pincfg.GP.cfg_b.eGPOutCfg = AM_HAL_GPIO_PIN_OUTCFG_PUSHPULL;
@@ -260,12 +270,23 @@ static int ambiq_gpio_port_get_direction(const struct device *dev, gpio_port_pin
 static int ambiq_gpio_port_get_raw(const struct device *dev, gpio_port_value_t *value)
 {
 	const struct ambiq_gpio_config *const dev_cfg = dev->config;
+	am_hal_gpio_pincfg_t pincfg;
+	uint32_t pin_offset;
 
 #if defined(CONFIG_SOC_SERIES_APOLLO3X)
-	*value = (*AM_HAL_GPIO_RDn(dev_cfg->offset));
+	pin_offset = dev_cfg->offset;
+	am_hal_gpio_pinconfig_get(pin_offset, &pincfg);
+	if (pincfg.eGPInput == AM_HAL_GPIO_PIN_INPUT_ENABLE) {
 #else
-	*value = (*AM_HAL_GPIO_RDn(dev_cfg->offset >> 2));
+	pin_offset = dev_cfg->offset >> 2;
+	am_hal_gpio_pinconfig_get(pin_offset, &pincfg);
+	if (pincfg.GP.cfg_b.eGPInput == AM_HAL_GPIO_PIN_INPUT_ENABLE) {
 #endif
+		*value = (*AM_HAL_GPIO_RDn(pin_offset));
+	} else {
+		*value = (*AM_HAL_GPIO_WTn(pin_offset));
+	}
+
 	return 0;
 }
 

drivers/i2c/Kconfig.ambiq

@@ -27,4 +27,10 @@ config I2C_DMA_TCB_BUFFER_SIZE
 	help
 	  DMA Transfer Control Buffer size in words
 
+config I2C_AMBIQ_BUS_RECOVERY
+	bool "Bus recovery support"
+	select I2C_BITBANG
+	help
+	  Enable AMBIQ driver bus recovery support via GPIO bitbanging.
+
 endif # I2C_AMBIQ

drivers/i2c/i2c_ambiq.c

@@ -15,6 +15,11 @@
 
 #include <am_mcu_apollo.h>
 
+#ifdef CONFIG_I2C_AMBIQ_BUS_RECOVERY
+#include <zephyr/drivers/gpio.h>
+#include "i2c_bitbang.h"
+#endif /* CONFIG_I2C_AMBIQ_BUS_RECOVERY */
+
 #include <zephyr/logging/log.h>
 #include <zephyr/drivers/pinctrl.h>
 
@@ -28,6 +33,10 @@ typedef int (*ambiq_i2c_pwr_func_t)(void);
 #include "i2c-priv.h"
 
 struct i2c_ambiq_config {
+#ifdef CONFIG_I2C_AMBIQ_BUS_RECOVERY
+	struct gpio_dt_spec scl;
+	struct gpio_dt_spec sda;
+#endif /* CONFIG_I2C_AMBIQ_BUS_RECOVERY */
 	uint32_t base;
 	int size;
 	uint32_t bitrate;
@@ -241,6 +250,90 @@ static int i2c_ambiq_transfer(const struct device *dev, struct i2c_msg *msgs, ui
 	return ret;
 }
 
+#if CONFIG_I2C_AMBIQ_BUS_RECOVERY
+static void i2c_ambiq_bitbang_set_scl(void *io_context, int state)
+{
+	const struct i2c_ambiq_config *config = io_context;
+
+	gpio_pin_set_dt(&config->scl, state);
+}
+
+static void i2c_ambiq_bitbang_set_sda(void *io_context, int state)
+{
+	const struct i2c_ambiq_config *config = io_context;
+
+	gpio_pin_set_dt(&config->sda, state);
+}
+
+static int i2c_ambiq_bitbang_get_sda(void *io_context)
+{
+	const struct i2c_ambiq_config *config = io_context;
+
+	return gpio_pin_get_dt(&config->sda) == 0 ? 0 : 1;
+}
+
+static int i2c_ambiq_recover_bus(const struct device *dev)
+{
+	const struct i2c_ambiq_config *config = dev->config;
+	struct i2c_ambiq_data *data = dev->data;
+	struct i2c_bitbang bitbang_ctx;
+	struct i2c_bitbang_io bitbang_io = {
+		.set_scl = i2c_ambiq_bitbang_set_scl,
+		.set_sda = i2c_ambiq_bitbang_set_sda,
+		.get_sda = i2c_ambiq_bitbang_get_sda,
+	};
+	uint32_t bitrate_cfg;
+	int error = 0;
+
+	LOG_ERR("attempting to recover bus");
+
+	if (!gpio_is_ready_dt(&config->scl)) {
+		LOG_ERR("SCL GPIO device not ready");
+		return -EIO;
+	}
+
+	if (!gpio_is_ready_dt(&config->sda)) {
+		LOG_ERR("SDA GPIO device not ready");
+		return -EIO;
+	}
+
+	k_sem_take(&data->bus_sem, K_FOREVER);
+
+	error = gpio_pin_configure_dt(&config->scl, GPIO_OUTPUT_HIGH);
+	if (error != 0) {
+		LOG_ERR("failed to configure SCL GPIO (err %d)", error);
+		goto restore;
+	}
+
+	error = gpio_pin_configure_dt(&config->sda, GPIO_OUTPUT_HIGH);
+	if (error != 0) {
+		LOG_ERR("failed to configure SDA GPIO (err %d)", error);
+		goto restore;
+	}
+
+	i2c_bitbang_init(&bitbang_ctx, &bitbang_io, (void *)config);
+
+	bitrate_cfg = i2c_map_dt_bitrate(config->bitrate) | I2C_MODE_CONTROLLER;
+	error = i2c_bitbang_configure(&bitbang_ctx, bitrate_cfg);
+	if (error != 0) {
+		LOG_ERR("failed to configure I2C bitbang (err %d)", error);
+		goto restore;
+	}
+
+	error = i2c_bitbang_recover_bus(&bitbang_ctx);
+	if (error != 0) {
+		LOG_ERR("failed to recover bus (err %d)", error);
+	}
+
+restore:
+	(void)pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
+
+	k_sem_give(&data->bus_sem);
+
+	return error;
+}
+#endif /* CONFIG_I2C_AMBIQ_BUS_RECOVERY */
+
 static int i2c_ambiq_init(const struct device *dev)
 {
 	struct i2c_ambiq_data *data = dev->data;
@@ -291,6 +384,9 @@ end:
 static const struct i2c_driver_api i2c_ambiq_driver_api = {
 	.configure = i2c_ambiq_configure,
 	.transfer = i2c_ambiq_transfer,
+#if CONFIG_I2C_AMBIQ_BUS_RECOVERY
+	.recover_bus = i2c_ambiq_recover_bus,
+#endif /* CONFIG_I2C_AMBIQ_BUS_RECOVERY */
 #ifdef CONFIG_I2C_RTIO
 	.iodev_submit = i2c_iodev_submit_fallback,
 #endif
@@ -351,7 +447,10 @@ static int i2c_ambiq_pm_action(const struct device *dev, enum pm_device_action a
 		.bitrate = DT_INST_PROP(n, clock_frequency),                                       \
 		.pcfg = PINCTRL_DT_INST_DEV_CONFIG_GET(n),                                         \
 		.irq_config_func = i2c_irq_config_func_##n,                                        \
-		.pwr_func = pwr_on_ambiq_i2c_##n};                                                 \
+		.pwr_func = pwr_on_ambiq_i2c_##n,                                                  \
+		IF_ENABLED(CONFIG_I2C_AMBIQ_BUS_RECOVERY,			\
+		(.scl = GPIO_DT_SPEC_INST_GET_OR(n, scl_gpios, {0}),\
+		 .sda = GPIO_DT_SPEC_INST_GET_OR(n, sda_gpios, {0}),)) };      \
 	PM_DEVICE_DT_INST_DEFINE(n, i2c_ambiq_pm_action);                                          \
 	I2C_DEVICE_DT_INST_DEFINE(n, i2c_ambiq_init, PM_DEVICE_DT_INST_GET(n), &i2c_ambiq_data##n, \
 				  &i2c_ambiq_config##n, POST_KERNEL, CONFIG_I2C_INIT_PRIORITY,     \

dts/bindings/i2c/ambiq,i2c.yaml

@@ -16,3 +16,15 @@ properties:
 
   ambiq,pwrcfg:
     required: true
+
+  scl-gpios:
+    type: phandle-array
+    description: |
+      GPIO to which the I2C SCL signal is routed. This is only needed for I2C bus recovery
+      support.
+
+  sda-gpios:
+    type: phandle-array
+    description: |
+      GPIO to which the I2C SDA signal is routed. This is only needed for I2C bus recovery
+      support.