[v3,2/6] i2c: at91: implement i2c bus recovery
diff mbox series

Message ID 20200115115422.17097-3-codrin.ciubotariu@microchip.com
State Accepted
Headers show
Series
  • i2c bus recovery for Microchip SoCs
Related show

Commit Message

Codrin Ciubotariu Jan. 15, 2020, 11:54 a.m. UTC
From: Kamel Bouhara <kamel.bouhara@bootlin.com>

Implement i2c bus recovery when slaves devices might hold SDA low.
In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses
until the slave release SDA.

Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
---

Changes in v3:
 - removed unnecessary condition from info print;
 - removed unneded declarations;

Changes in v2:
 - called i2c_recover_bus() after an error occurs, if SDA is down;
 - release gpios if recovery information is incomplete;

 drivers/i2c/busses/i2c-at91-master.c | 78 ++++++++++++++++++++++++++++
 drivers/i2c/busses/i2c-at91.h        |  4 ++
 2 files changed, 82 insertions(+)

Comments

Ludovic Desroches Jan. 27, 2020, 8:50 a.m. UTC | #1
On Wed, Jan 15, 2020 at 01:54:18PM +0200, Codrin Ciubotariu wrote:
> From: Kamel Bouhara <kamel.bouhara@bootlin.com>
> 
> Implement i2c bus recovery when slaves devices might hold SDA low.
> In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses
> until the slave release SDA.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

> ---
> 
> Changes in v3:
>  - removed unnecessary condition from info print;
>  - removed unneded declarations;
> 
> Changes in v2:
>  - called i2c_recover_bus() after an error occurs, if SDA is down;
>  - release gpios if recovery information is incomplete;
> 
>  drivers/i2c/busses/i2c-at91-master.c | 78 ++++++++++++++++++++++++++++
>  drivers/i2c/busses/i2c-at91.h        |  4 ++
>  2 files changed, 82 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
> index 7a862e00b475..0aba51a7df32 100644
> --- a/drivers/i2c/busses/i2c-at91-master.c
> +++ b/drivers/i2c/busses/i2c-at91-master.c
> @@ -18,11 +18,13 @@
>  #include <linux/dma-mapping.h>
>  #include <linux/dmaengine.h>
>  #include <linux/err.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/i2c.h>
>  #include <linux/interrupt.h>
>  #include <linux/io.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/platform_data/dma-atmel.h>
>  #include <linux/pm_runtime.h>
> @@ -478,6 +480,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
>  	unsigned long time_left;
>  	bool has_unre_flag = dev->pdata->has_unre_flag;
>  	bool has_alt_cmd = dev->pdata->has_alt_cmd;
> +	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
>  
>  	/*
>  	 * WARNING: the TXCOMP bit in the Status Register is NOT a clear on
> @@ -637,6 +640,13 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
>  		at91_twi_write(dev, AT91_TWI_CR,
>  			       AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
>  	}
> +
> +	if (rinfo->get_sda && !(rinfo->get_sda(&dev->adapter))) {
> +		dev_dbg(dev->dev,
> +			"SDA is down; clear bus using gpio\n");
> +		i2c_recover_bus(&dev->adapter);
> +	}
> +
>  	return ret;
>  }
>  
> @@ -806,6 +816,70 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
>  	return ret;
>  }
>  
> +static void at91_prepare_twi_recovery(struct i2c_adapter *adap)
> +{
> +	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
> +
> +	pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_gpio);
> +}
> +
> +static void at91_unprepare_twi_recovery(struct i2c_adapter *adap)
> +{
> +	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
> +
> +	pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default);
> +}
> +
> +static int at91_init_twi_recovery_info(struct platform_device *pdev,
> +				       struct at91_twi_dev *dev)
> +{
> +	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
> +
> +	dev->pinctrl = devm_pinctrl_get(&pdev->dev);
> +	if (!dev->pinctrl || IS_ERR(dev->pinctrl)) {
> +		dev_info(dev->dev, "can't get pinctrl, bus recovery not supported\n");
> +		return PTR_ERR(dev->pinctrl);
> +	}
> +
> +	dev->pinctrl_pins_default = pinctrl_lookup_state(dev->pinctrl,
> +							 PINCTRL_STATE_DEFAULT);
> +	dev->pinctrl_pins_gpio = pinctrl_lookup_state(dev->pinctrl,
> +						      "gpio");
> +	rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
> +	if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER)
> +		return -EPROBE_DEFER;
> +
> +	rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl",
> +					  GPIOD_OUT_HIGH_OPEN_DRAIN);
> +	if (PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER)
> +		return -EPROBE_DEFER;
> +
> +	if (IS_ERR(rinfo->sda_gpiod) ||
> +	    IS_ERR(rinfo->scl_gpiod) ||
> +	    IS_ERR(dev->pinctrl_pins_default) ||
> +	    IS_ERR(dev->pinctrl_pins_gpio)) {
> +		dev_info(&pdev->dev, "recovery information incomplete\n");
> +		if (!IS_ERR(rinfo->sda_gpiod)) {
> +			gpiod_put(rinfo->sda_gpiod);
> +			rinfo->sda_gpiod = NULL;
> +		}
> +		if (!IS_ERR(rinfo->scl_gpiod)) {
> +			gpiod_put(rinfo->scl_gpiod);
> +			rinfo->scl_gpiod = NULL;
> +		}
> +		return -EINVAL;
> +	}
> +
> +	dev_info(&pdev->dev, "using scl, sda for recovery\n");
> +
> +	rinfo->prepare_recovery = at91_prepare_twi_recovery;
> +	rinfo->unprepare_recovery = at91_unprepare_twi_recovery;
> +	rinfo->recover_bus = i2c_generic_scl_recovery;
> +	dev->adapter.bus_recovery_info = rinfo;
> +
> +	return 0;
> +}
> +
>  int at91_twi_probe_master(struct platform_device *pdev,
>  			  u32 phy_addr, struct at91_twi_dev *dev)
>  {
> @@ -838,6 +912,10 @@ int at91_twi_probe_master(struct platform_device *pdev,
>  						     "i2c-analog-filter");
>  	at91_calc_twi_clock(dev);
>  
> +	rc = at91_init_twi_recovery_info(pdev, dev);
> +	if (rc == -EPROBE_DEFER)
> +		return rc;
> +
>  	dev->adapter.algo = &at91_twi_algorithm;
>  	dev->adapter.quirks = &at91_twi_quirks;
>  
> diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h
> index 977a67bc0f88..f57a6cab96b4 100644
> --- a/drivers/i2c/busses/i2c-at91.h
> +++ b/drivers/i2c/busses/i2c-at91.h
> @@ -151,6 +151,10 @@ struct at91_twi_dev {
>  	u32 fifo_size;
>  	struct at91_twi_dma dma;
>  	bool slave_detected;
> +	struct i2c_bus_recovery_info rinfo;
> +	struct pinctrl *pinctrl;
> +	struct pinctrl_state *pinctrl_pins_default;
> +	struct pinctrl_state *pinctrl_pins_gpio;
>  #ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL
>  	unsigned smr;
>  	struct i2c_client *slave;
> -- 
> 2.20.1
>
Wolfram Sang Feb. 22, 2020, 11:33 a.m. UTC | #2
On Wed, Jan 15, 2020 at 01:54:18PM +0200, Codrin Ciubotariu wrote:
> From: Kamel Bouhara <kamel.bouhara@bootlin.com>
> 
> Implement i2c bus recovery when slaves devices might hold SDA low.
> In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses
> until the slave release SDA.
> 
> Signed-off-by: Kamel Bouhara <kamel.bouhara@bootlin.com>
> Signed-off-by: Codrin Ciubotariu <codrin.ciubotariu@microchip.com>

Applied to for-next, thanks!

The implementation is very similar to i2c-imx. Maybe we should move this
mechanism into the core somewhen...

Patch
diff mbox series

diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index 7a862e00b475..0aba51a7df32 100644
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -18,11 +18,13 @@ 
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/err.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/pinctrl/consumer.h>
 #include <linux/platform_device.h>
 #include <linux/platform_data/dma-atmel.h>
 #include <linux/pm_runtime.h>
@@ -478,6 +480,7 @@  static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 	unsigned long time_left;
 	bool has_unre_flag = dev->pdata->has_unre_flag;
 	bool has_alt_cmd = dev->pdata->has_alt_cmd;
+	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
 
 	/*
 	 * WARNING: the TXCOMP bit in the Status Register is NOT a clear on
@@ -637,6 +640,13 @@  static int at91_do_twi_transfer(struct at91_twi_dev *dev)
 		at91_twi_write(dev, AT91_TWI_CR,
 			       AT91_TWI_THRCLR | AT91_TWI_LOCKCLR);
 	}
+
+	if (rinfo->get_sda && !(rinfo->get_sda(&dev->adapter))) {
+		dev_dbg(dev->dev,
+			"SDA is down; clear bus using gpio\n");
+		i2c_recover_bus(&dev->adapter);
+	}
+
 	return ret;
 }
 
@@ -806,6 +816,70 @@  static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr)
 	return ret;
 }
 
+static void at91_prepare_twi_recovery(struct i2c_adapter *adap)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
+
+	pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_gpio);
+}
+
+static void at91_unprepare_twi_recovery(struct i2c_adapter *adap)
+{
+	struct at91_twi_dev *dev = i2c_get_adapdata(adap);
+
+	pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default);
+}
+
+static int at91_init_twi_recovery_info(struct platform_device *pdev,
+				       struct at91_twi_dev *dev)
+{
+	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
+
+	dev->pinctrl = devm_pinctrl_get(&pdev->dev);
+	if (!dev->pinctrl || IS_ERR(dev->pinctrl)) {
+		dev_info(dev->dev, "can't get pinctrl, bus recovery not supported\n");
+		return PTR_ERR(dev->pinctrl);
+	}
+
+	dev->pinctrl_pins_default = pinctrl_lookup_state(dev->pinctrl,
+							 PINCTRL_STATE_DEFAULT);
+	dev->pinctrl_pins_gpio = pinctrl_lookup_state(dev->pinctrl,
+						      "gpio");
+	rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN);
+	if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl",
+					  GPIOD_OUT_HIGH_OPEN_DRAIN);
+	if (PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER)
+		return -EPROBE_DEFER;
+
+	if (IS_ERR(rinfo->sda_gpiod) ||
+	    IS_ERR(rinfo->scl_gpiod) ||
+	    IS_ERR(dev->pinctrl_pins_default) ||
+	    IS_ERR(dev->pinctrl_pins_gpio)) {
+		dev_info(&pdev->dev, "recovery information incomplete\n");
+		if (!IS_ERR(rinfo->sda_gpiod)) {
+			gpiod_put(rinfo->sda_gpiod);
+			rinfo->sda_gpiod = NULL;
+		}
+		if (!IS_ERR(rinfo->scl_gpiod)) {
+			gpiod_put(rinfo->scl_gpiod);
+			rinfo->scl_gpiod = NULL;
+		}
+		return -EINVAL;
+	}
+
+	dev_info(&pdev->dev, "using scl, sda for recovery\n");
+
+	rinfo->prepare_recovery = at91_prepare_twi_recovery;
+	rinfo->unprepare_recovery = at91_unprepare_twi_recovery;
+	rinfo->recover_bus = i2c_generic_scl_recovery;
+	dev->adapter.bus_recovery_info = rinfo;
+
+	return 0;
+}
+
 int at91_twi_probe_master(struct platform_device *pdev,
 			  u32 phy_addr, struct at91_twi_dev *dev)
 {
@@ -838,6 +912,10 @@  int at91_twi_probe_master(struct platform_device *pdev,
 						     "i2c-analog-filter");
 	at91_calc_twi_clock(dev);
 
+	rc = at91_init_twi_recovery_info(pdev, dev);
+	if (rc == -EPROBE_DEFER)
+		return rc;
+
 	dev->adapter.algo = &at91_twi_algorithm;
 	dev->adapter.quirks = &at91_twi_quirks;
 
diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h
index 977a67bc0f88..f57a6cab96b4 100644
--- a/drivers/i2c/busses/i2c-at91.h
+++ b/drivers/i2c/busses/i2c-at91.h
@@ -151,6 +151,10 @@  struct at91_twi_dev {
 	u32 fifo_size;
 	struct at91_twi_dma dma;
 	bool slave_detected;
+	struct i2c_bus_recovery_info rinfo;
+	struct pinctrl *pinctrl;
+	struct pinctrl_state *pinctrl_pins_default;
+	struct pinctrl_state *pinctrl_pins_gpio;
 #ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL
 	unsigned smr;
 	struct i2c_client *slave;