[PATCH linux dev-4.7 4/5] drivers/fsi: Add FSI bus error cleanup

[Eddie James]

Acked-by: Eddie James <eajames at linux.vnet.ibm.com>


On 02/16/2017 04:04 PM, Christopher Bostic wrote:
> On detect of bus fails attempt to clean them up and try the
> command again.
>
> Signed-off-by: Christopher Bostic <cbostic at linux.vnet.ibm.com>
> ---
>   drivers/fsi/fsi-master-gpio.c | 100 +++++++++++++++++++++++++++++++++++-------
>   1 file changed, 85 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/fsi/fsi-master-gpio.c b/drivers/fsi/fsi-master-gpio.c
> index 92af53d..bb3983c 100644
> --- a/drivers/fsi/fsi-master-gpio.c
> +++ b/drivers/fsi/fsi-master-gpio.c
> @@ -67,8 +67,16 @@
>
>   #define	FSI_MASTER_GPIO_LINK_SIZE	0x00800000
>
> +static int fsi_master_gpio_read(struct fsi_master *_master, int link,
> +		uint8_t slave, uint32_t addr, void *val, size_t size);
> +static int fsi_master_gpio_write(struct fsi_master *_master, int link,
> +		uint8_t slave, uint32_t addr, const void *val, size_t size);
> +static int fsi_master_gpio_break(struct fsi_master *_master, int link);
> +
>   static DEFINE_SPINLOCK(fsi_gpio_cmd_lock);	/* lock around fsi commands */
>
> +uint8_t in_err_cleanup;
> +
>   struct fsi_master_gpio {
>   	struct fsi_master	master;
>   	struct gpio_desc	*gpio_clk;
> @@ -358,24 +366,85 @@ static void build_abs_ar_command(struct fsi_gpio_msg *cmd, uint64_t mode,
>   	cmd->msg >>= (64 - cmd->bits);
>   }
>
> +/*
> + * Clean up the FSI bus path on detection of error.
> + * todo: get rid of magic numbers
> + */
> +static void fsi_master_gpio_handle_error(struct fsi_master_gpio *master,
> +					uint32_t addr)
> +{
> +	uint32_t smode = 0xa0ff0100;
> +
> +	/* Avoid nested error handling */
> +	if (in_err_cleanup)
> +		return;
> +
> +	in_err_cleanup = 1;
> +	fsi_master_gpio_break(&master->master, 0);
> +	udelay(200);
> +
> +	/* Set slave ID in smode */
> +	fsi_master_gpio_write(&master->master, 0, 0, 0x800, &smode,
> +				sizeof(smode));
> +
> +	/* Reset the MFSI bridge */
> +	smode = 0xc0000000;
> +	fsi_master_gpio_write(&master->master, 0, 0, 0x35D0, &smode,
> +				sizeof(smode));
> +
> +	if (addr >= 0x80000) {
> +
> +		/*
> +		 * Break to hub link 1
> +		 * todo: make this handle more arbitrary link topologies
> +		 */
> +		smode = 0xc0de0000;
> +		fsi_master_gpio_write(&master->master, 0, 0, 0x100004, &smode,
> +					sizeof(smode));
> +
> +		smode = 0xa0ff0100;
> +		fsi_master_gpio_write(&master->master, 0, 0, 0x100800, &smode,
> +					sizeof(smode));
> +	}
> +	in_err_cleanup = 0;
> +}
> +
> +static int send_command(struct fsi_master_gpio *master,
> +			struct fsi_gpio_msg *cmd, uint8_t expected,
> +			size_t size, void *val)
> +{
> +	unsigned long flags;
> +	int rc;
> +
> +	spin_lock_irqsave(&fsi_gpio_cmd_lock, flags);
> +	serial_out(master, cmd);
> +	echo_delay(master);
> +	rc = poll_for_response(master, expected, size, val);
> +	spin_unlock_irqrestore(&fsi_gpio_cmd_lock, flags);
> +
> +	return rc;
> +}
> +
>   static int fsi_master_gpio_read(struct fsi_master *_master, int link,
>   		uint8_t slave, uint32_t addr, void *val, size_t size)
>   {
>   	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
>   	struct fsi_gpio_msg cmd;
>   	int rc;
> -	unsigned long flags;
>
>   	if (link != 0)
>   		return -ENODEV;
>
>   	build_abs_ar_command(&cmd, FSI_GPIO_CMD_READ, slave, addr, size, NULL);
> -
> -	spin_lock_irqsave(&fsi_gpio_cmd_lock, flags);
> -	serial_out(master, &cmd);
> -	echo_delay(master);
> -	rc = poll_for_response(master, FSI_GPIO_RESP_ACKD, size, val);
> -	spin_unlock_irqrestore(&fsi_gpio_cmd_lock, flags);
> +	rc = send_command(master, &cmd, FSI_GPIO_RESP_ACKD, size, val);
> +	if (rc) {
> +		fsi_master_gpio_handle_error(master, addr);
> +
> +		/* Try again */
> +		rc = send_command(master, &cmd, FSI_GPIO_RESP_ACKD, size, val);
> +		if (rc)
> +			fsi_master_gpio_handle_error(master, addr);
> +	}
>
>   	return rc;
>   }
> @@ -386,18 +455,20 @@ static int fsi_master_gpio_write(struct fsi_master *_master, int link,
>   	struct fsi_master_gpio *master = to_fsi_master_gpio(_master);
>   	struct fsi_gpio_msg cmd;
>   	int rc;
> -	unsigned long flags;
>
>   	if (link != 0)
>   		return -ENODEV;
>
>   	build_abs_ar_command(&cmd, FSI_GPIO_CMD_WRITE, slave, addr, size, val);
> -
> -	spin_lock_irqsave(&fsi_gpio_cmd_lock, flags);
> -	serial_out(master, &cmd);
> -	echo_delay(master);
> -	rc = poll_for_response(master, FSI_GPIO_RESP_ACK, size, NULL);
> -	spin_unlock_irqrestore(&fsi_gpio_cmd_lock, flags);
> +	rc = send_command(master, &cmd, FSI_GPIO_RESP_ACK, size, NULL);
> +	if (rc) {
> +		fsi_master_gpio_handle_error(master, addr);
> +
> +		/* Try again */
> +		rc = send_command(master, &cmd, FSI_GPIO_RESP_ACK, size, NULL);
> +		if (rc)
> +			fsi_master_gpio_handle_error(master, addr);
> +	}
>
>   	return rc;
>   }
> @@ -480,7 +551,6 @@ static int fsi_master_gpio_probe(struct platform_device *pdev)
>   	master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
>   	if (!master)
>   		return -ENOMEM;
> -	master->master.dev = &pdev->dev;
>
>   	gpio = devm_gpiod_get(&pdev->dev, "clock", 0);
>   	if (IS_ERR(gpio)) {