[PATCH v3] libata: pata_samsung_cf: Add Samsung PATA controller driver

[Ben Dooks]

On Thu, Jun 10, 2010 at 02:43:34PM +0400, Sergei Shtylyov wrote:
> Kukjin Kim wrote:
>
>> From: Abhilash Kesavan <a.kesavan at samsung.com>
>
>> Adds support for the Samsung PATA controller. This driver is based on the
>> Libata subsystem and references the earlier patches sent for IDE subsystem.
>
>> Signed-off-by: Abhilash Kesavan <a.kesavan at samsung.com>
>> Signed-off-by: Kukjin Kim <kgene.kim at samsung.com>
>
> [...]
>
>> diff --git a/drivers/ata/pata_samsung_cf.c b/drivers/ata/pata_samsung_cf.c
>> new file mode 100644
>> index 0000000..fef5515
>> --- /dev/null
>> +++ b/drivers/ata/pata_samsung_cf.c
>> @@ -0,0 +1,608 @@
>> +/* linux/drivers/ata/pata_samsung_cf.c
>
>    File names in the heading comment are discouraged.
>
> [...]

>> +static void pata_s3c_set_piomode(struct ata_port *ap, struct ata_device *adev)
>> +{
>> +	int mode = adev->pio_mode - XFER_PIO_0;
>> +	struct s3c_ide_info *info = ap->host->private_data;
>> +	ulong ata_cfg = readl(info->ide_addr + S3C_ATA_CFG);
>> +	ulong piotime;
>> +
>> +	/* Calculates timing parameters for PIO mode */
>> +	piotime = pata_s3c_setup_timing(info, adev);
>
>    In fact, for 8-bit (command) timing you should program the slowest 
> mode of the two drives. However, with CF, you probably only have only one 
> drive per channel...
>
>> +
>> +	/* Enables IORDY if mode requires it */
>> +	if (ata_pio_need_iordy(adev))
>> +		ata_cfg |= S3C_ATA_CFG_IORDYEN;
>> +	else
>> +		ata_cfg &= ~S3C_ATA_CFG_IORDYEN;
>> +
>> +	/* Host controller supports upto PIO4 only */
>> +	if (mode >= 0 && mode <= 4) {
>
>    No need to check -- you won't be passed a mode not specified by your pio_mask.

probably not even worth bthering with a WARN_ON() for this.

.> +		writel(ata_cfg, info->ide_addr + S3C_ATA_CFG);
>> +		writel(piotime, info->ide_addr + S3C_ATA_PIO_TIME);
>> +	}
>> +}
>
> [...]
>
>> +/*
>> + * pata_s3c_data_xfer - Transfer data by PIO
>> + */
>> +unsigned int pata_s3c_data_xfer(struct ata_device *dev, unsigned char *buf,
>> +				unsigned int buflen, int rw)
>> +{
>> +	struct ata_port *ap = dev->link->ap;
>> +	struct s3c_ide_info *info = ap->host->private_data;
>> +	void __iomem *data_addr = ap->ioaddr.data_addr;
>> +	unsigned int words = buflen >> 1, i;
>> +	u16 *data_ptr = (u16 *)buf;
>> +
>> +	if (rw == READ)
>> +		for (i = 0; i < words; i++, data_ptr++) {
>> +			wait_for_host_ready(info);
>> +			*data_ptr = readw(data_addr);
>
>    Why not just ignore the result?


possibly (void)readw(data_addr);

>> +			wait_for_host_ready(info);
>> +			*data_ptr = readw(info->ide_addr
>> +					+ S3C_ATA_PIO_RDATA);
>> +		}

It would be nice to have a description of why we're throwing data
away from the FIFO.

>> +	else
>> +		for (i = 0; i < words; i++, data_ptr++) {
>> +			wait_for_host_ready(info);
>> +			writel(*data_ptr, data_addr);
>> +		}

For the write case, would it be better to read the FIFO free lvel
and then then write that many words each time?

>> +	return words << 1;
>> +}
>
> [...]
>
>> +static struct ata_port_operations pata_s3c_port_ops = {
>> +	.inherits		= &ata_sff_port_ops,
>> +	.sff_check_status	= pata_s3c_check_status,
>> +	.sff_check_altstatus    = pata_s3c_check_altstatus,
>> +	.sff_tf_load		= pata_s3c_tf_load,
>> +	.sff_tf_read		= pata_s3c_tf_read,
>> +	.sff_data_xfer		= pata_s3c_data_xfer,
>> +	.sff_exec_command	= pata_s3c_exec_command,
>> +	.sff_dev_select         = pata_s3c_dev_select,
>> +	.sff_set_devctl         = pata_s3c_set_devctl,
>
>    I forgot: you also need to override the softreset() method as it 
> accesses several taskfile registers and ioread8()/iowrite8() won't 
> suffice -- Jeff was too quick to ack the patch. See ata_bus_softreset(), 
> ata_devchk(), and ata_sff_wait_after_reset() for the accesses I'm talking 
> about...
>
> [...]
>
>> +static int __devinit pata_s3c_probe(struct platform_device *pdev)
>> +{
>> +	struct s3c_ide_platdata *pdata = pdev->dev.platform_data;
>> +	struct device *dev = &pdev->dev;
>> +	struct s3c_ide_info *info;
>> +	struct resource *res;
>> +	struct ata_port *ap;
>> +	struct ata_host *host;
>> +	enum s3c_cpu_type cpu_type;
>> +	int ret;
>> +
>> +	cpu_type = platform_get_device_id(pdev)->driver_data;
>> +
>> +	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
>> +	if (!info) {
>> +		dev_err(dev, "failed to allocate memory for device data\n");
>> +		return -ENOMEM;
>> +	}
>> +
>> +	info->irq = platform_get_irq(pdev, 0);
>> +	if (info->irq < 0) {
>> +		dev_err(dev, "could not obtain irq number\n");
>> +		ret = -EINVAL;
>> +		goto release_device_mem;
>> +	}
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (res == NULL) {
>> +		dev_err(dev, "failed to get mem resource\n");
>> +		ret = -EINVAL;
>> +		goto release_device_mem;
>> +	}
>> +
>> +	if (!request_mem_region(res->start, resource_size(res), DRV_NAME)) {
>
>    Probably should call devm_request_mem_region() if you're using  
> devm_ioremap()...
>
>> +		dev_err(dev, "error requesting register region\n");
>> +		return -EBUSY;
>> +	}
>> +
>> +	info->ide_addr = devm_ioremap(dev, res->start, resource_size(res));
>> +	if (!info->ide_addr) {
>> +		dev_err(dev, "failed to map IO base address\n");
>> +		ret = -ENOMEM;
>> +		goto release_mem;
>> +	}
>> +
>> +	info->clk = clk_get(&pdev->dev, "cfcon");
>> +	if (IS_ERR(info->clk)) {
>> +		dev_err(dev, "failed to get access to cf controller clock\n");
>> +		ret = PTR_ERR(info->clk);
>> +		info->clk = NULL;

We really need to get away from passing a clock name here.

-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.