Re: [PATCH v3 5/8] drivers/soc: xdma: Add PCI device configuration sysfs

[Eduardo Valentin <eduval@amazon.com>]

On Wed, May 29, 2019 at 01:10:05PM -0500, Eddie James wrote:
> The AST2500 has two PCI devices embedded. The XDMA engine can use either
> device to perform DMA transfers. Users need the capability to choose
> which device to use. This commit therefore adds two sysfs files that
> toggle the AST2500 and XDMA engine between the two PCI devices.
> 
> Signed-off-by: Eddie James <eajames@linux.ibm.com>
> ---
>  drivers/soc/aspeed/aspeed-xdma.c | 103 +++++++++++++++++++++++++++++++++++++--
>  1 file changed, 100 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/soc/aspeed/aspeed-xdma.c b/drivers/soc/aspeed/aspeed-xdma.c
> index 39f6545..ddd5e1e 100644
> --- a/drivers/soc/aspeed/aspeed-xdma.c
> +++ b/drivers/soc/aspeed/aspeed-xdma.c
> @@ -143,6 +143,7 @@ struct aspeed_xdma {
>  	void *cmdq_vga_virt;
>  	struct gen_pool *vga_pool;
>  
> +	char pcidev[4];
>  	struct miscdevice misc;
>  };
>  
> @@ -165,6 +166,10 @@ struct aspeed_xdma_client {
>  	SCU_PCIE_CONF_VGA_EN_IRQ | SCU_PCIE_CONF_VGA_EN_DMA |
>  	SCU_PCIE_CONF_RSVD;
>  
> +static char *_pcidev = "vga";
> +module_param_named(pcidev, _pcidev, charp, 0600);
> +MODULE_PARM_DESC(pcidev, "Default PCI device used by XDMA engine for DMA ops");
> +
>  static void aspeed_scu_pcie_write(struct aspeed_xdma *ctx, u32 conf)
>  {
>  	u32 v = 0;
> @@ -512,7 +517,7 @@ static int aspeed_xdma_release(struct inode *inode, struct file *file)
>  	.release		= aspeed_xdma_release,
>  };
>  
> -static int aspeed_xdma_init_mem(struct aspeed_xdma *ctx)
> +static int aspeed_xdma_init_mem(struct aspeed_xdma *ctx, u32 conf)
>  {
>  	int rc;
>  	u32 scu_conf = 0;
> @@ -522,7 +527,7 @@ static int aspeed_xdma_init_mem(struct aspeed_xdma *ctx)
>  	const u32 vga_sizes[4] = { 0x800000, 0x1000000, 0x2000000, 0x4000000 };
>  	void __iomem *sdmc_base = ioremap(0x1e6e0000, 0x100);
>  
> -	aspeed_scu_pcie_write(ctx, aspeed_xdma_vga_pcie_conf);
> +	aspeed_scu_pcie_write(ctx, conf);
>  
>  	regmap_read(ctx->scu, SCU_STRAP, &scu_conf);
>  	ctx->vga_size = vga_sizes[FIELD_GET(SCU_STRAP_VGA_MEM, scu_conf)];
> @@ -598,10 +603,91 @@ static int aspeed_xdma_init_mem(struct aspeed_xdma *ctx)
>  	return rc;
>  }
>  
> +static int aspeed_xdma_change_pcie_conf(struct aspeed_xdma *ctx, u32 conf)
> +{
> +	int rc;
> +
> +	mutex_lock(&ctx->start_lock);
> +	rc = wait_event_interruptible_timeout(ctx->wait,
> +					      !test_bit(XDMA_IN_PRG,
> +							&ctx->flags),
> +					      msecs_to_jiffies(1000));
> +	if (rc < 0) {
> +		mutex_unlock(&ctx->start_lock);
> +		return -EINTR;
> +	}
> +
> +	/* previous op didn't complete, wake up waiters anyway */
> +	if (!rc)
> +		wake_up_interruptible_all(&ctx->wait);
> +
> +	reset_control_assert(ctx->reset);
> +	msleep(10);
> +
> +	aspeed_scu_pcie_write(ctx, conf);
> +	msleep(10);
> +
> +	reset_control_deassert(ctx->reset);
> +	msleep(10);
> +
> +	aspeed_xdma_init_eng(ctx);
> +
> +	mutex_unlock(&ctx->start_lock);
> +
> +	return 0;
> +}
> +
> +static int aspeed_xdma_pcidev_to_conf(struct aspeed_xdma *ctx,
> +				      const char *pcidev, u32 *conf)
> +{
> +	if (!strcasecmp(pcidev, "vga")) {
> +		*conf = aspeed_xdma_vga_pcie_conf;
> +		return 0;
> +	}
> +
> +	if (!strcasecmp(pcidev, "bmc")) {
> +		*conf = aspeed_xdma_bmc_pcie_conf;
> +		return 0;
> +	}

strncasecmp()?

> +
> +	return -EINVAL;
> +}
> +
> +static ssize_t aspeed_xdma_show_pcidev(struct device *dev,
> +				       struct device_attribute *attr,
> +				       char *buf)
> +{
> +	struct aspeed_xdma *ctx = dev_get_drvdata(dev);
> +
> +	return snprintf(buf, PAGE_SIZE - 1, "%s", ctx->pcidev);
> +}
> +
> +static ssize_t aspeed_xdma_store_pcidev(struct device *dev,
> +					struct device_attribute *attr,
> +					const char *buf, size_t count)
> +{
> +	u32 conf;
> +	struct aspeed_xdma *ctx = dev_get_drvdata(dev);
> +	int rc = aspeed_xdma_pcidev_to_conf(ctx, buf, &conf);
> +
> +	if (rc)
> +		return rc;
> +
> +	rc = aspeed_xdma_change_pcie_conf(ctx, conf);
> +	if (rc)
> +		return rc;
> +
> +	strcpy(ctx->pcidev, buf);

should we use strncpy() instead?

> +	return count;
> +}
> +static DEVICE_ATTR(pcidev, 0644, aspeed_xdma_show_pcidev,
> +		   aspeed_xdma_store_pcidev);
> +
>  static int aspeed_xdma_probe(struct platform_device *pdev)
>  {
>  	int irq;
>  	int rc;
> +	u32 conf;
>  	struct resource *res;
>  	struct device *dev = &pdev->dev;
>  	struct aspeed_xdma *ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
> @@ -657,7 +743,14 @@ static int aspeed_xdma_probe(struct platform_device *pdev)
>  
>  	msleep(10);
>  
> -	rc = aspeed_xdma_init_mem(ctx);
> +	if (aspeed_xdma_pcidev_to_conf(ctx, _pcidev, &conf)) {
> +		conf = aspeed_xdma_vga_pcie_conf;
> +		strcpy(ctx->pcidev, "vga");
> +	} else {
> +		strcpy(ctx->pcidev, _pcidev);
> +	}

same...

> +
> +	rc = aspeed_xdma_init_mem(ctx, conf);
>  	if (rc) {
>  		reset_control_assert(ctx->reset);
>  		return rc;
> @@ -682,6 +775,8 @@ static int aspeed_xdma_probe(struct platform_device *pdev)
>  		return rc;
>  	}
>  
> +	device_create_file(dev, &dev_attr_pcidev);

Should we consider using one of the default attributes here instead of device_create_file()?
http://kroah.com/log/blog/2013/06/26/how-to-create-a-sysfs-file-correctly/

BTW, was this ABI documented? Is this the same file documented in patch 2?

> +
>  	return 0;
>  }
>  
> @@ -689,6 +784,8 @@ static int aspeed_xdma_remove(struct platform_device *pdev)
>  {
>  	struct aspeed_xdma *ctx = platform_get_drvdata(pdev);
>  
> +	device_remove_file(ctx->dev, &dev_attr_pcidev);
> +
>  	misc_deregister(&ctx->misc);
>  	gen_pool_free(ctx->vga_pool, (unsigned long)ctx->cmdq_vga_virt,
>  		      XDMA_CMDQ_SIZE);
> -- 
> 1.8.3.1
> 

-- 
All the best,
Eduardo Valentin