[PATCH] i2c: bcm-iproc: Add i2c recovery support

[PATCH] i2c: bcm-iproc: Add i2c recovery support

[Chris Packham]

From: Richard Laing <richard.laing@alliedtelesis.co.nz>

The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
make use of this to support i2c bus recovery.

Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
---

Notes:
    Richard did most of the work on this. I'm just cleaning it up to get it
    upstream.

 drivers/i2c/busses/i2c-bcm-iproc.c | 115 +++++++++++++++++++++++++++++
 1 file changed, 115 insertions(+)

diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
index cceaf69279a9..d63a286c1660 100644
--- a/drivers/i2c/busses/i2c-bcm-iproc.c
+++ b/drivers/i2c/busses/i2c-bcm-iproc.c
@@ -26,6 +26,7 @@
 #define CFG_RESET_SHIFT              31
 #define CFG_EN_SHIFT                 30
 #define CFG_SLAVE_ADDR_0_SHIFT       28
+#define CFG_BIT_BANG_SHIFT           29
 #define CFG_M_RETRY_CNT_SHIFT        16
 #define CFG_M_RETRY_CNT_MASK         0x0f
 
@@ -66,6 +67,12 @@
 #define S_FIFO_RX_THLD_SHIFT         8
 #define S_FIFO_RX_THLD_MASK          0x3f
 
+#define M_BB_CTRL_OFFSET             0x14
+#define M_BB_SMBCLK_IN               31
+#define M_BB_SMBCLK_OUT_EN           30
+#define M_BB_SMBDAT_IN               29
+#define M_BB_SMBDAT_OUT_EN           28
+
 #define M_CMD_OFFSET                 0x30
 #define M_CMD_START_BUSY_SHIFT       31
 #define M_CMD_STATUS_SHIFT           25
@@ -713,6 +720,112 @@ static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
 	iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
 }
 
+static void bcm_iproc_i2c_reset(struct bcm_iproc_i2c_dev *iproc_i2c)
+{
+	u32 tmp;
+
+	tmp = readl(iproc_i2c->base + CFG_OFFSET);
+	tmp |= BIT(CFG_RESET_SHIFT);
+	writel(tmp, iproc_i2c->base + CFG_OFFSET);
+	udelay(100);
+
+}
+
+static void bcm_iproc_i2c_prepare_recovery(struct i2c_adapter *adap)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	dev_dbg(iproc_i2c->device, "Prepare recovery\n");
+
+	/* Disable interrupts */
+	writel(0, iproc_i2c->base + IE_OFFSET);
+	readl(iproc_i2c->base + IE_OFFSET);
+	synchronize_irq(iproc_i2c->irq);
+
+	bcm_iproc_i2c_reset(iproc_i2c);
+
+	/* Switch to bit-bang mode */
+	tmp = readl(iproc_i2c->base + CFG_OFFSET);
+	tmp |= BIT(CFG_BIT_BANG_SHIFT);
+	writel(tmp, iproc_i2c->base + CFG_OFFSET);
+}
+
+static void bcm_iproc_i2c_unprepare_recovery(struct i2c_adapter *adap)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	/* Switch to normal mode */
+	tmp = readl(iproc_i2c->base + CFG_OFFSET);
+	tmp &= ~BIT(CFG_BIT_BANG_SHIFT);
+	writel(tmp, iproc_i2c->base + CFG_OFFSET);
+	udelay(100);
+
+	bcm_iproc_i2c_init(iproc_i2c);
+	bcm_iproc_i2c_enable_disable(iproc_i2c, true);
+
+	dev_dbg(iproc_i2c->device, "Recovery complete\n");
+}
+
+static int bcm_iproc_i2c_get_scl(struct i2c_adapter *adap)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
+
+	return !!(tmp & BIT(M_BB_SMBCLK_IN));
+}
+
+static void bcm_iproc_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
+	if (val)
+		tmp |= BIT(M_BB_SMBCLK_OUT_EN);
+	else
+		tmp &= ~BIT(M_BB_SMBCLK_OUT_EN);
+
+	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
+}
+
+static void bcm_iproc_i2c_set_sda(struct i2c_adapter *adap, int val)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
+	if (val)
+		tmp |= BIT(M_BB_SMBDAT_OUT_EN);
+	else
+		tmp &= ~BIT(M_BB_SMBDAT_OUT_EN);
+
+	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
+}
+
+static int bcm_iproc_i2c_get_sda(struct i2c_adapter *adap)
+{
+	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
+	u32 tmp;
+
+	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
+
+	return !!(tmp & BIT(M_BB_SMBDAT_IN));
+}
+
+static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {
+	.recover_bus = i2c_generic_scl_recovery,
+	.prepare_recovery = bcm_iproc_i2c_prepare_recovery,
+	.unprepare_recovery = bcm_iproc_i2c_unprepare_recovery,
+	.set_scl = bcm_iproc_i2c_set_scl,
+	.get_scl = bcm_iproc_i2c_get_scl,
+	.set_sda = bcm_iproc_i2c_set_sda,
+	.get_sda = bcm_iproc_i2c_get_sda,
+};
+
 static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
 				      struct i2c_msg *msg)
 {
@@ -839,6 +952,7 @@ static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
 	if (!!(iproc_i2c_rd_reg(iproc_i2c,
 				M_CMD_OFFSET) & BIT(M_CMD_START_BUSY_SHIFT))) {
 		dev_warn(iproc_i2c->device, "bus is busy\n");
+		i2c_recover_bus(&iproc_i2c->adapter);
 		return -EBUSY;
 	}
 
@@ -1111,6 +1225,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
 		of_node_full_name(iproc_i2c->device->of_node));
 	adap->algo = &bcm_iproc_algo;
 	adap->quirks = &bcm_iproc_i2c_quirks;
+	adap->bus_recovery_info = &bcm_iproc_recovery_info;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
 
-- 
2.31.1


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Re: [PATCH] i2c: bcm-iproc: Add i2c recovery support

[Ray Jui]

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On 5/30/2021 3:56 PM, Chris Packham wrote:
> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
> 
> The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
> make use of this to support i2c bus recovery.
> 
> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
> ---
> 
> Notes:
>     Richard did most of the work on this. I'm just cleaning it up to get it
>     upstream.
> 
>  drivers/i2c/busses/i2c-bcm-iproc.c | 115 +++++++++++++++++++++++++++++
>  1 file changed, 115 insertions(+)
> 
> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
> index cceaf69279a9..d63a286c1660 100644
> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
> @@ -26,6 +26,7 @@
>  #define CFG_RESET_SHIFT              31
>  #define CFG_EN_SHIFT                 30
>  #define CFG_SLAVE_ADDR_0_SHIFT       28
> +#define CFG_BIT_BANG_SHIFT           29

move this up one line (to be consistent with existing bit order)

>  #define CFG_M_RETRY_CNT_SHIFT        16
>  #define CFG_M_RETRY_CNT_MASK         0x0f
>  
> @@ -66,6 +67,12 @@
>  #define S_FIFO_RX_THLD_SHIFT         8
>  #define S_FIFO_RX_THLD_MASK          0x3f
>  
> +#define M_BB_CTRL_OFFSET             0x14
> +#define M_BB_SMBCLK_IN               31

M_BB_CTRL_CLK_IN_SHIFT, ket is to have '_SHIFT' to be consistent with
existing code

> +#define M_BB_SMBCLK_OUT_EN           30

M_BB_CTRL_CLK_OUT_SHIFT

> +#define M_BB_SMBDAT_IN               29

M_BB_CTRL_DATA_IN_SHIFT

> +#define M_BB_SMBDAT_OUT_EN           28

M_BB_CTRL_DATA_OUT_SHIFT

> +
>  #define M_CMD_OFFSET                 0x30
>  #define M_CMD_START_BUSY_SHIFT       31
>  #define M_CMD_STATUS_SHIFT           25
> @@ -713,6 +720,112 @@ static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
>  	iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
>  }
>  
> +static void bcm_iproc_i2c_reset(struct bcm_iproc_i2c_dev *iproc_i2c)
> +{
> +	u32 tmp;
> +
> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
> +	tmp |= BIT(CFG_RESET_SHIFT);
> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
> +	udelay(100);

This puts the controller in reset and hold it there, but never brings
the controller out of reset (bcm_iproc_i2c_init called in unprepare
brings the controller out of reset)

Calling it a "reset" function is a bit misleading to me. My expectation
of a reset function is that you generate a reset pulse, ie.g., reset ->
delay -> out of reset.

Why don't you simply put this seuquence of code in the prepare_recovery
function below, instead of calling this a reset function?

> +
> +}
> +
> +static void bcm_iproc_i2c_prepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	dev_dbg(iproc_i2c->device, "Prepare recovery\n");
> +
> +	/* Disable interrupts */
> +	writel(0, iproc_i2c->base + IE_OFFSET);
> +	readl(iproc_i2c->base + IE_OFFSET);
> +	synchronize_irq(iproc_i2c->irq);
> +
> +	bcm_iproc_i2c_reset(iproc_i2c);
> +
> +	/* Switch to bit-bang mode */
> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
> +	tmp |= BIT(CFG_BIT_BANG_SHIFT);
> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);

add usleep_range(100, 200) here, required delay after switching to bit
bang based on spec.

> +}
> +
> +static void bcm_iproc_i2c_unprepare_recovery(struct i2c_adapter *adap)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	/* Switch to normal mode */
> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
> +	tmp &= ~BIT(CFG_BIT_BANG_SHIFT);
> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
> +	udelay(100);
> +
> +	bcm_iproc_i2c_init(iproc_i2c);

Add sequence to re-configure to desired bus speed here after the reset
sequence (someone else in our team tested this is required to resume to
proper bus speed).

> +	bcm_iproc_i2c_enable_disable(iproc_i2c, true);
> +
> +	dev_dbg(iproc_i2c->device, "Recovery complete\n");
> +}
> +
> +static int bcm_iproc_i2c_get_scl(struct i2c_adapter *adap)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
> +
> +	return !!(tmp & BIT(M_BB_SMBCLK_IN));
> +}
> +
> +static void bcm_iproc_i2c_set_scl(struct i2c_adapter *adap, int val)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
> +	if (val)
> +		tmp |= BIT(M_BB_SMBCLK_OUT_EN);
> +	else
> +		tmp &= ~BIT(M_BB_SMBCLK_OUT_EN);
> +
> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
> +}
> +
> +static void bcm_iproc_i2c_set_sda(struct i2c_adapter *adap, int val)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
> +	if (val)
> +		tmp |= BIT(M_BB_SMBDAT_OUT_EN);
> +	else
> +		tmp &= ~BIT(M_BB_SMBDAT_OUT_EN);
> +
> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
> +}
> +
> +static int bcm_iproc_i2c_get_sda(struct i2c_adapter *adap)
> +{
> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
> +	u32 tmp;
> +
> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
> +
> +	return !!(tmp & BIT(M_BB_SMBDAT_IN));
> +}
> +
> +static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {

static const struct ...

> +	.recover_bus = i2c_generic_scl_recovery,
> +	.prepare_recovery = bcm_iproc_i2c_prepare_recovery,
> +	.unprepare_recovery = bcm_iproc_i2c_unprepare_recovery,
> +	.set_scl = bcm_iproc_i2c_set_scl,
> +	.get_scl = bcm_iproc_i2c_get_scl,
> +	.set_sda = bcm_iproc_i2c_set_sda,
> +	.get_sda = bcm_iproc_i2c_get_sda,
> +};
> +
>  static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
>  				      struct i2c_msg *msg)
>  {
> @@ -839,6 +952,7 @@ static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
>  	if (!!(iproc_i2c_rd_reg(iproc_i2c,
>  				M_CMD_OFFSET) & BIT(M_CMD_START_BUSY_SHIFT))) {
>  		dev_warn(iproc_i2c->device, "bus is busy\n");
> +		i2c_recover_bus(&iproc_i2c->adapter);

'i2c_recover_bus' should not be ALWAYS called here. You don't know if
bus is actually locked up or it's other issues that caused this.

We need a logic to detect and confirm the lock up condition before
committing to recover operation:

/* Check if bus lockup occurred, and invoke recovery if so. */
static void iproc_i2c_lockup_recover(struct bcm_iproc_i2c_dev *iproc_i2c)
{
	/*
	 * assume bus lockup if SDA line is low;
	 * note that there is no need to switch to
	 * bit-bang mode for this check.
	 */
	if (!bcm_iproc_i2c_get_sda(&iproc_i2c->adapter)) {
		/* locked up - invoke i2c bus recovery. */
		int ret = i2c_recover_bus(&iproc_i2c->adapter);
			if (ret)
				dev_err(iproc_i2c->device,
					"bus recovery: error %d\n",
					ret);
	}
}

'iproc_i2c_lockup_recover' should be called in two locations in the driver:

1. After 'transaction timed out' (and after flush both TX/RX FIFOS)
2. After 'bcm_iproc_i2c_check_status' failures (and after flush both
TX/RX FIFOs).

>  		return -EBUSY;
>  	}
>  
> @@ -1111,6 +1225,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
>  		of_node_full_name(iproc_i2c->device->of_node));
>  	adap->algo = &bcm_iproc_algo;
>  	adap->quirks = &bcm_iproc_i2c_quirks;
> +	adap->bus_recovery_info = &bcm_iproc_recovery_info;
>  	adap->dev.parent = &pdev->dev;
>  	adap->dev.of_node = pdev->dev.of_node;
>  
> 

Thanks,

Ray

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Re: [PATCH] i2c: bcm-iproc: Add i2c recovery support

[Chris Packham]

On 2/06/21 9:03 am, Ray Jui wrote:
>
> On 5/30/2021 3:56 PM, Chris Packham wrote:
>> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>
>> The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
>> make use of this to support i2c bus recovery.
>>
>> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> ---
>>
>> Notes:
>>      Richard did most of the work on this. I'm just cleaning it up to get it
>>      upstream.
>>
>>   drivers/i2c/busses/i2c-bcm-iproc.c | 115 +++++++++++++++++++++++++++++
>>   1 file changed, 115 insertions(+)
>>
>> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
>> index cceaf69279a9..d63a286c1660 100644
>> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
>> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
>> @@ -26,6 +26,7 @@
>>   #define CFG_RESET_SHIFT              31
>>   #define CFG_EN_SHIFT                 30
>>   #define CFG_SLAVE_ADDR_0_SHIFT       28
>> +#define CFG_BIT_BANG_SHIFT           29
> move this up one line (to be consistent with existing bit order)

Ack.

>>   #define CFG_M_RETRY_CNT_SHIFT        16
>>   #define CFG_M_RETRY_CNT_MASK         0x0f
>>   
>> @@ -66,6 +67,12 @@
>>   #define S_FIFO_RX_THLD_SHIFT         8
>>   #define S_FIFO_RX_THLD_MASK          0x3f
>>   
>> +#define M_BB_CTRL_OFFSET             0x14
>> +#define M_BB_SMBCLK_IN               31
> M_BB_CTRL_CLK_IN_SHIFT, ket is to have '_SHIFT' to be consistent with
> existing code

Ack.

>> +#define M_BB_SMBCLK_OUT_EN           30
> M_BB_CTRL_CLK_OUT_SHIFT
>
>> +#define M_BB_SMBDAT_IN               29
> M_BB_CTRL_DATA_IN_SHIFT
>
>> +#define M_BB_SMBDAT_OUT_EN           28
> M_BB_CTRL_DATA_OUT_SHIFT
>
>> +
>>   #define M_CMD_OFFSET                 0x30
>>   #define M_CMD_START_BUSY_SHIFT       31
>>   #define M_CMD_STATUS_SHIFT           25
>> @@ -713,6 +720,112 @@ static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
>>   	iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
>>   }
>>   
>> +static void bcm_iproc_i2c_reset(struct bcm_iproc_i2c_dev *iproc_i2c)
>> +{
>> +	u32 tmp;
>> +
>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>> +	tmp |= BIT(CFG_RESET_SHIFT);
>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
>> +	udelay(100);
> This puts the controller in reset and hold it there, but never brings
> the controller out of reset (bcm_iproc_i2c_init called in unprepare
> brings the controller out of reset)
>
> Calling it a "reset" function is a bit misleading to me. My expectation
> of a reset function is that you generate a reset pulse, ie.g., reset ->
> delay -> out of reset.
>
> Why don't you simply put this seuquence of code in the prepare_recovery
> function below, instead of calling this a reset function?

Will do. Should I also change the udelay(100) to a usleep_range(100, 
200)? Same question for the other uses of udelay().

>
>> +
>> +}
>> +
>> +static void bcm_iproc_i2c_prepare_recovery(struct i2c_adapter *adap)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	dev_dbg(iproc_i2c->device, "Prepare recovery\n");
>> +
>> +	/* Disable interrupts */
>> +	writel(0, iproc_i2c->base + IE_OFFSET);
>> +	readl(iproc_i2c->base + IE_OFFSET);
>> +	synchronize_irq(iproc_i2c->irq);
>> +
>> +	bcm_iproc_i2c_reset(iproc_i2c);
>> +
>> +	/* Switch to bit-bang mode */
>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>> +	tmp |= BIT(CFG_BIT_BANG_SHIFT);
>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
> add usleep_range(100, 200) here, required delay after switching to bit
> bang based on spec.

Ack.

>
>> +}
>> +
>> +static void bcm_iproc_i2c_unprepare_recovery(struct i2c_adapter *adap)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	/* Switch to normal mode */
>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>> +	tmp &= ~BIT(CFG_BIT_BANG_SHIFT);
>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
>> +	udelay(100);
>> +
>> +	bcm_iproc_i2c_init(iproc_i2c);
> Add sequence to re-configure to desired bus speed here after the reset
> sequence (someone else in our team tested this is required to resume to
> proper bus speed).
bcm_iproc_i2c_resume() seems to have the exact sequence I need. If I 
move it outside of CONFIG_PM_SLEEP I could just call it here.
>> +	bcm_iproc_i2c_enable_disable(iproc_i2c, true);
>> +
>> +	dev_dbg(iproc_i2c->device, "Recovery complete\n");
>> +}
>> +
>> +static int bcm_iproc_i2c_get_scl(struct i2c_adapter *adap)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +
>> +	return !!(tmp & BIT(M_BB_SMBCLK_IN));
>> +}
>> +
>> +static void bcm_iproc_i2c_set_scl(struct i2c_adapter *adap, int val)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +	if (val)
>> +		tmp |= BIT(M_BB_SMBCLK_OUT_EN);
>> +	else
>> +		tmp &= ~BIT(M_BB_SMBCLK_OUT_EN);
>> +
>> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +}
>> +
>> +static void bcm_iproc_i2c_set_sda(struct i2c_adapter *adap, int val)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +	if (val)
>> +		tmp |= BIT(M_BB_SMBDAT_OUT_EN);
>> +	else
>> +		tmp &= ~BIT(M_BB_SMBDAT_OUT_EN);
>> +
>> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +}
>> +
>> +static int bcm_iproc_i2c_get_sda(struct i2c_adapter *adap)
>> +{
>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>> +	u32 tmp;
>> +
>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>> +
>> +	return !!(tmp & BIT(M_BB_SMBDAT_IN));
>> +}
>> +
>> +static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {
> static const struct ...
Ack.
>> +	.recover_bus = i2c_generic_scl_recovery,
>> +	.prepare_recovery = bcm_iproc_i2c_prepare_recovery,
>> +	.unprepare_recovery = bcm_iproc_i2c_unprepare_recovery,
>> +	.set_scl = bcm_iproc_i2c_set_scl,
>> +	.get_scl = bcm_iproc_i2c_get_scl,
>> +	.set_sda = bcm_iproc_i2c_set_sda,
>> +	.get_sda = bcm_iproc_i2c_get_sda,
>> +};
>> +
>>   static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
>>   				      struct i2c_msg *msg)
>>   {
>> @@ -839,6 +952,7 @@ static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
>>   	if (!!(iproc_i2c_rd_reg(iproc_i2c,
>>   				M_CMD_OFFSET) & BIT(M_CMD_START_BUSY_SHIFT))) {
>>   		dev_warn(iproc_i2c->device, "bus is busy\n");
>> +		i2c_recover_bus(&iproc_i2c->adapter);
> 'i2c_recover_bus' should not be ALWAYS called here. You don't know if
> bus is actually locked up or it's other issues that caused this.
>
> We need a logic to detect and confirm the lock up condition before
> committing to recover operation:
>
> /* Check if bus lockup occurred, and invoke recovery if so. */
> static void iproc_i2c_lockup_recover(struct bcm_iproc_i2c_dev *iproc_i2c)
> {
> 	/*
> 	 * assume bus lockup if SDA line is low;
> 	 * note that there is no need to switch to
> 	 * bit-bang mode for this check.
> 	 */
> 	if (!bcm_iproc_i2c_get_sda(&iproc_i2c->adapter)) {
> 		/* locked up - invoke i2c bus recovery. */
> 		int ret = i2c_recover_bus(&iproc_i2c->adapter);
> 			if (ret)
> 				dev_err(iproc_i2c->device,
> 					"bus recovery: error %d\n",
> 					ret);
> 	}
> }
>
> 'iproc_i2c_lockup_recover' should be called in two locations in the driver:
>
> 1. After 'transaction timed out' (and after flush both TX/RX FIFOS)
> 2. After 'bcm_iproc_i2c_check_status' failures (and after flush both
> TX/RX FIFOs).

I see bcm_iproc_i2c_check_status() has a "recovery" case on an unknown 
error. Should I remove that if I'm going to call 
iproc_i2c_lockup_recover() or check for ret != -EIO?

>
>>   		return -EBUSY;
>>   	}
>>   
>> @@ -1111,6 +1225,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
>>   		of_node_full_name(iproc_i2c->device->of_node));
>>   	adap->algo = &bcm_iproc_algo;
>>   	adap->quirks = &bcm_iproc_i2c_quirks;
>> +	adap->bus_recovery_info = &bcm_iproc_recovery_info;
>>   	adap->dev.parent = &pdev->dev;
>>   	adap->dev.of_node = pdev->dev.of_node;
>>   
>>
> Thanks,
>
> Ray
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Re: [PATCH] i2c: bcm-iproc: Add i2c recovery support

[Ray Jui]

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On 6/1/2021 2:44 PM, Chris Packham wrote:
> 
> On 2/06/21 9:03 am, Ray Jui wrote:
>>
>> On 5/30/2021 3:56 PM, Chris Packham wrote:
>>> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>>
>>> The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
>>> make use of this to support i2c bus recovery.
>>>
>>> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>> ---
>>>
>>> Notes:
>>>      Richard did most of the work on this. I'm just cleaning it up to get it
>>>      upstream.
>>>
>>>   drivers/i2c/busses/i2c-bcm-iproc.c | 115 +++++++++++++++++++++++++++++
>>>   1 file changed, 115 insertions(+)
>>>
>>> diff --git a/drivers/i2c/busses/i2c-bcm-iproc.c b/drivers/i2c/busses/i2c-bcm-iproc.c
>>> index cceaf69279a9..d63a286c1660 100644
>>> --- a/drivers/i2c/busses/i2c-bcm-iproc.c
>>> +++ b/drivers/i2c/busses/i2c-bcm-iproc.c
>>> @@ -26,6 +26,7 @@
>>>   #define CFG_RESET_SHIFT              31
>>>   #define CFG_EN_SHIFT                 30
>>>   #define CFG_SLAVE_ADDR_0_SHIFT       28
>>> +#define CFG_BIT_BANG_SHIFT           29
>> move this up one line (to be consistent with existing bit order)
> 
> Ack.
> 
>>>   #define CFG_M_RETRY_CNT_SHIFT        16
>>>   #define CFG_M_RETRY_CNT_MASK         0x0f
>>>   
>>> @@ -66,6 +67,12 @@
>>>   #define S_FIFO_RX_THLD_SHIFT         8
>>>   #define S_FIFO_RX_THLD_MASK          0x3f
>>>   
>>> +#define M_BB_CTRL_OFFSET             0x14
>>> +#define M_BB_SMBCLK_IN               31
>> M_BB_CTRL_CLK_IN_SHIFT, ket is to have '_SHIFT' to be consistent with
>> existing code
> 
> Ack.
> 
>>> +#define M_BB_SMBCLK_OUT_EN           30
>> M_BB_CTRL_CLK_OUT_SHIFT
>>
>>> +#define M_BB_SMBDAT_IN               29
>> M_BB_CTRL_DATA_IN_SHIFT
>>
>>> +#define M_BB_SMBDAT_OUT_EN           28
>> M_BB_CTRL_DATA_OUT_SHIFT
>>
>>> +
>>>   #define M_CMD_OFFSET                 0x30
>>>   #define M_CMD_START_BUSY_SHIFT       31
>>>   #define M_CMD_STATUS_SHIFT           25
>>> @@ -713,6 +720,112 @@ static void bcm_iproc_i2c_enable_disable(struct bcm_iproc_i2c_dev *iproc_i2c,
>>>   	iproc_i2c_wr_reg(iproc_i2c, CFG_OFFSET, val);
>>>   }
>>>   
>>> +static void bcm_iproc_i2c_reset(struct bcm_iproc_i2c_dev *iproc_i2c)
>>> +{
>>> +	u32 tmp;
>>> +
>>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>>> +	tmp |= BIT(CFG_RESET_SHIFT);
>>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
>>> +	udelay(100);
>> This puts the controller in reset and hold it there, but never brings
>> the controller out of reset (bcm_iproc_i2c_init called in unprepare
>> brings the controller out of reset)
>>
>> Calling it a "reset" function is a bit misleading to me. My expectation
>> of a reset function is that you generate a reset pulse, ie.g., reset ->
>> delay -> out of reset.
>>
>> Why don't you simply put this seuquence of code in the prepare_recovery
>> function below, instead of calling this a reset function?
> 
> Will do. Should I also change the udelay(100) to a usleep_range(100, 
> 200)? Same question for the other uses of udelay().
> 

Sure I think that makes sense.

>>
>>> +
>>> +}
>>> +
>>> +static void bcm_iproc_i2c_prepare_recovery(struct i2c_adapter *adap)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	dev_dbg(iproc_i2c->device, "Prepare recovery\n");
>>> +
>>> +	/* Disable interrupts */
>>> +	writel(0, iproc_i2c->base + IE_OFFSET);
>>> +	readl(iproc_i2c->base + IE_OFFSET);
>>> +	synchronize_irq(iproc_i2c->irq);
>>> +
>>> +	bcm_iproc_i2c_reset(iproc_i2c);
>>> +
>>> +	/* Switch to bit-bang mode */
>>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>>> +	tmp |= BIT(CFG_BIT_BANG_SHIFT);
>>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
>> add usleep_range(100, 200) here, required delay after switching to bit
>> bang based on spec.
> 
> Ack.
> 
>>
>>> +}
>>> +
>>> +static void bcm_iproc_i2c_unprepare_recovery(struct i2c_adapter *adap)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	/* Switch to normal mode */
>>> +	tmp = readl(iproc_i2c->base + CFG_OFFSET);
>>> +	tmp &= ~BIT(CFG_BIT_BANG_SHIFT);
>>> +	writel(tmp, iproc_i2c->base + CFG_OFFSET);
>>> +	udelay(100);
>>> +
>>> +	bcm_iproc_i2c_init(iproc_i2c);
>> Add sequence to re-configure to desired bus speed here after the reset
>> sequence (someone else in our team tested this is required to resume to
>> proper bus speed).
> bcm_iproc_i2c_resume() seems to have the exact sequence I need. If I 
> move it outside of CONFIG_PM_SLEEP I could just call it here.

Yes agree with you that 'bcm_iproc_i2c_resume' can be resued.

>>> +	bcm_iproc_i2c_enable_disable(iproc_i2c, true);
>>> +
>>> +	dev_dbg(iproc_i2c->device, "Recovery complete\n");
>>> +}
>>> +
>>> +static int bcm_iproc_i2c_get_scl(struct i2c_adapter *adap)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +
>>> +	return !!(tmp & BIT(M_BB_SMBCLK_IN));
>>> +}
>>> +
>>> +static void bcm_iproc_i2c_set_scl(struct i2c_adapter *adap, int val)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +	if (val)
>>> +		tmp |= BIT(M_BB_SMBCLK_OUT_EN);
>>> +	else
>>> +		tmp &= ~BIT(M_BB_SMBCLK_OUT_EN);
>>> +
>>> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +}
>>> +
>>> +static void bcm_iproc_i2c_set_sda(struct i2c_adapter *adap, int val)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +	if (val)
>>> +		tmp |= BIT(M_BB_SMBDAT_OUT_EN);
>>> +	else
>>> +		tmp &= ~BIT(M_BB_SMBDAT_OUT_EN);
>>> +
>>> +	writel(tmp, iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +}
>>> +
>>> +static int bcm_iproc_i2c_get_sda(struct i2c_adapter *adap)
>>> +{
>>> +	struct bcm_iproc_i2c_dev *iproc_i2c = i2c_get_adapdata(adap);
>>> +	u32 tmp;
>>> +
>>> +	tmp = readl(iproc_i2c->base + M_BB_CTRL_OFFSET);
>>> +
>>> +	return !!(tmp & BIT(M_BB_SMBDAT_IN));
>>> +}
>>> +
>>> +static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {
>> static const struct ...
> Ack.
>>> +	.recover_bus = i2c_generic_scl_recovery,
>>> +	.prepare_recovery = bcm_iproc_i2c_prepare_recovery,
>>> +	.unprepare_recovery = bcm_iproc_i2c_unprepare_recovery,
>>> +	.set_scl = bcm_iproc_i2c_set_scl,
>>> +	.get_scl = bcm_iproc_i2c_get_scl,
>>> +	.set_sda = bcm_iproc_i2c_set_sda,
>>> +	.get_sda = bcm_iproc_i2c_get_sda,
>>> +};
>>> +
>>>   static int bcm_iproc_i2c_check_status(struct bcm_iproc_i2c_dev *iproc_i2c,
>>>   				      struct i2c_msg *msg)
>>>   {
>>> @@ -839,6 +952,7 @@ static int bcm_iproc_i2c_xfer_internal(struct bcm_iproc_i2c_dev *iproc_i2c,
>>>   	if (!!(iproc_i2c_rd_reg(iproc_i2c,
>>>   				M_CMD_OFFSET) & BIT(M_CMD_START_BUSY_SHIFT))) {
>>>   		dev_warn(iproc_i2c->device, "bus is busy\n");
>>> +		i2c_recover_bus(&iproc_i2c->adapter);
>> 'i2c_recover_bus' should not be ALWAYS called here. You don't know if
>> bus is actually locked up or it's other issues that caused this.
>>
>> We need a logic to detect and confirm the lock up condition before
>> committing to recover operation:
>>
>> /* Check if bus lockup occurred, and invoke recovery if so. */
>> static void iproc_i2c_lockup_recover(struct bcm_iproc_i2c_dev *iproc_i2c)
>> {
>> 	/*
>> 	 * assume bus lockup if SDA line is low;
>> 	 * note that there is no need to switch to
>> 	 * bit-bang mode for this check.
>> 	 */
>> 	if (!bcm_iproc_i2c_get_sda(&iproc_i2c->adapter)) {
>> 		/* locked up - invoke i2c bus recovery. */
>> 		int ret = i2c_recover_bus(&iproc_i2c->adapter);
>> 			if (ret)
>> 				dev_err(iproc_i2c->device,
>> 					"bus recovery: error %d\n",
>> 					ret);
>> 	}
>> }
>>
>> 'iproc_i2c_lockup_recover' should be called in two locations in the driver:
>>
>> 1. After 'transaction timed out' (and after flush both TX/RX FIFOS)
>> 2. After 'bcm_iproc_i2c_check_status' failures (and after flush both
>> TX/RX FIFOs).
> 
> I see bcm_iproc_i2c_check_status() has a "recovery" case on an unknown 
> error. Should I remove that if I'm going to call 
> iproc_i2c_lockup_recover() or check for ret != -EIO?
> 

You may leave that (as first level recovery due to some potential
internal ASIC issues).

Let iproc_i2c_lockup_recover handles the bus lockup type of recovery
(after confirming the bus is indeed locked up).

>>
>>>   		return -EBUSY;
>>>   	}
>>>   
>>> @@ -1111,6 +1225,7 @@ static int bcm_iproc_i2c_probe(struct platform_device *pdev)
>>>   		of_node_full_name(iproc_i2c->device->of_node));
>>>   	adap->algo = &bcm_iproc_algo;
>>>   	adap->quirks = &bcm_iproc_i2c_quirks;
>>> +	adap->bus_recovery_info = &bcm_iproc_recovery_info;
>>>   	adap->dev.parent = &pdev->dev;
>>>   	adap->dev.of_node = pdev->dev.of_node;
>>>   
>>>
>> Thanks,
>>
>> Ray

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Re: [PATCH] i2c: bcm-iproc: Add i2c recovery support

[Chris Packham]

On 2/06/21 9:03 am, Ray Jui wrote:
>
> On 5/30/2021 3:56 PM, Chris Packham wrote:
>> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>
>> The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
>> make use of this to support i2c bus recovery.
>>
>> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>> ---
<snip>
> +
>> +static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {
> static const struct ...

The kernel test bot doesn't like the suggestion.

 >> drivers/i2c/busses/i2c-bcm-iproc.c:1264:26: error: assigning to 
'struct i2c_bus_recovery_info *' from 'const struct 
i2c_bus_recovery_info *' discards qualifiers 
[-Werror,-Wincompatible-pointer-types-discards-qualifiers]

            adap->bus_recovery_info = &bcm_iproc_recovery_info;
                                    ^ ~~~~~~~~~~~~~~~~~~~~~~~~

I can see why. Are you happy for me to drop the const in v3? Or perhaps 
you have a better suggestion.
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Re: [PATCH] i2c: bcm-iproc: Add i2c recovery support

[Ray Jui]

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On 6/1/2021 7:32 PM, Chris Packham wrote:
> 
> On 2/06/21 9:03 am, Ray Jui wrote:
>>
>> On 5/30/2021 3:56 PM, Chris Packham wrote:
>>> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>>
>>> The bcm-iproc controller can put the SDA/SCL lines into bit-bang mode,
>>> make use of this to support i2c bus recovery.
>>>
>>> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>
>>> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
>>> ---
> <snip>
>> +
>>> +static struct i2c_bus_recovery_info bcm_iproc_recovery_info = {
>> static const struct ...
> 
> The kernel test bot doesn't like the suggestion.
> 
>  >> drivers/i2c/busses/i2c-bcm-iproc.c:1264:26: error: assigning to 
> 'struct i2c_bus_recovery_info *' from 'const struct 
> i2c_bus_recovery_info *' discards qualifiers 
> [-Werror,-Wincompatible-pointer-types-discards-qualifiers]
> 
>             adap->bus_recovery_info = &bcm_iproc_recovery_info;
>                                     ^ ~~~~~~~~~~~~~~~~~~~~~~~~
> 
> I can see why. Are you happy for me to drop the const in v3? Or perhaps 
> you have a better suggestion.
> 

Yeah of course. Please drop it. Sorry I missed that while making that
suggestion.

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