Re: [PATCH 1/2] i2c-s3c2410: Rework device type handling

Karol Lewandowski
2012-03-12T13:16:31Z

On 12.03.2012 06:58, Thomas Abraham wrote:

Hi Thomas!

> On 9 March 2012 22:34, Karol Lewandowski <k.lewandowsk-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org> wrote:
>> Reorganize driver a bit to better handle device tree-based systems:
>>
>> - move machine type to driver's private structure instead of
>> quering platform device variants in runtime
>>
>> - replace s3c24xx_i2c_type enum with plain unsigned int that can
>> hold not only device type but also hw revision-specific quirks
>>
>> Signed-off-by: Karol Lewandowski <k.lewandowsk-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> Signed-off-by: Kyungmin Park <kyungmin.park-Sze3O3UU22JBDgjK7y7TUQ@public.gmane.org>
>> ---
>> drivers/i2c/busses/i2c-s3c2410.c | 56 +++++++++++++------------------------
>> 1 files changed, 20 insertions(+), 36 deletions(-)
>>
>> diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
>> index 737f721..5b400c6 100644
>> --- a/drivers/i2c/busses/i2c-s3c2410.c
>> +++ b/drivers/i2c/busses/i2c-s3c2410.c
>> @@ -44,8 +44,12 @@
>> #include <plat/regs-iic.h>
>> #include <plat/iic.h>
>>
>> -/* i2c controller state */
>> +/* type */
>> +#define TYPE_BITS 0x000000ff
>> +#define TYPE_S3C2410 0x00000001
>> +#define TYPE_S3C2440 0x00000002
>>
>> +/* i2c controller state */
>> enum s3c24xx_i2c_state {
>> STATE_IDLE,
>> STATE_START,
>> @@ -54,14 +58,10 @@ enum s3c24xx_i2c_state {
>> STATE_STOP
>> };
>>
>> -enum s3c24xx_i2c_type {
>> - TYPE_S3C2410,
>> - TYPE_S3C2440,
>> -};
>> -
>> struct s3c24xx_i2c {
>> spinlock_t lock;
>> wait_queue_head_t wait;
>> + unsigned int type;
>> unsigned int suspended:1;
>>
>> struct i2c_msg *msg;
>> @@ -88,28 +88,6 @@ struct s3c24xx_i2c {
>> #endif
>> };
>>
>> -/* default platform data removed, dev should always carry data. */
>> -
>> -/* s3c24xx_i2c_is2440()
>> - *
>> - * return true is this is an s3c2440
>> -*/
>> -
>> -static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
>> -{
>> - struct platform_device *pdev = to_platform_device(i2c->dev);
>> - enum s3c24xx_i2c_type type;
>> -
>> -#ifdef CONFIG_OF
>> - if (i2c->dev->of_node)
>> - return of_device_is_compatible(i2c->dev->of_node,
>> - "samsung,s3c2440-i2c");
>> -#endif
>> -
>> - type = platform_get_device_id(pdev)->driver_data;
>> - return type == TYPE_S3C2440;
>> -}
>> -
>> /* s3c24xx_i2c_master_complete
>> *
>> * complete the message and wake up the caller, using the given return code,
>> @@ -676,7 +654,7 @@ static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
>>
>> writel(iiccon, i2c->regs + S3C2410_IICCON);
>>
>> - if (s3c24xx_i2c_is2440(i2c)) {
>> + if (i2c->type & TYPE_S3C2440) {
>
> This should be changed to
> if (i2c->type == TYPE_S3C2440)

Equality check won't work here after second patch is applied
(i2c->type might have FLAG_*s set on upper bits).

>
>> unsigned long sda_delay;
>>
>> if (pdata->sda_delay) {
>> @@ -847,6 +825,8 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
>> }
>>
>> #ifdef CONFIG_OF
>> +static const struct of_device_id s3c24xx_i2c_match[];
>> +
>> /* s3c24xx_i2c_parse_dt
>> *
>> * Parse the device tree node and retreive the platform data.
>> @@ -856,11 +836,16 @@ static void
>> s3c24xx_i2c_parse_dt(struct device_node *np, struct s3c24xx_i2c *i2c)
>> {
>> struct s3c2410_platform_i2c *pdata = i2c->pdata;
>> + const struct of_device_id *match;
>>
>> if (!np)
>> return;
>>
>> pdata->bus_num = -1; /* i2c bus number is dynamically assigned */
>> +
>> + match = of_match_node(&s3c24xx_i2c_match[0], np);
>
> This could be
> match = of_match_node(s3c24xx_i2c_match, np);

If you (and Ben, of course) don't mind I would prefer more verbose but
also more explicit version.

>> + i2c->type = (unsigned int)match->data;
>> +
>
> This function (s3c24xx_i2c_parse_dt) is intended to retrieve the data
> from i2c device node. It would be better to not add the determination
> of the i2c type inside this function.
>
>> of_property_read_u32(np, "samsung,i2c-sda-delay", &pdata->sda_delay);
>> of_property_read_u32(np, "samsung,i2c-slave-addr", &pdata->slave_addr);
>> of_property_read_u32(np, "samsung,i2c-max-bus-freq",
>> @@ -906,9 +891,10 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
>> goto err_noclk;
>> }
>>
>> - if (pdata)
>> + if (pdata) {
>> memcpy(i2c->pdata, pdata, sizeof(*pdata));
>> - else
>> + i2c->type = platform_get_device_id(pdev)->driver_data;
>> + } else
>> s3c24xx_i2c_parse_dt(pdev->dev.of_node, i2c);
>
> It would be better to move the task of retrieving the driver data to a
> separate function. An example of this listed below (copied from the
> samsung uart driver).

Well, I was under impression that #ifdefs inside functions were quite
disliked by kernel devs. Now I see that these are quite common in kernel..
Thus, I will happily use your suggestion, thanks.

>
> static inline struct s3c24xx_serial_drv_data *s3c24xx_get_driver_data(
> struct platform_device *pdev)
> {
> #ifdef CONFIG_OF
> if (pdev->dev.of_node) {
> const struct of_device_id *match;
> match = of_match_node(s3c24xx_uart_dt_match, pdev->dev.of_node);
> return (struct s3c24xx_serial_drv_data *)match->data;
> }
> #endif
> return (struct s3c24xx_serial_drv_data *)
> platform_get_device_id(pdev)->driver_data;
> }
>
>>
>> strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name));
>> @@ -1123,13 +1109,11 @@ MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);
>>
>> #ifdef CONFIG_OF
>> static const struct of_device_id s3c24xx_i2c_match[] = {
>> - { .compatible = "samsung,s3c2410-i2c" },
>> - { .compatible = "samsung,s3c2440-i2c" },
>> + { .compatible = "samsung,s3c2410-i2c", .data = (void *)TYPE_S3C2410 },
>> + { .compatible = "samsung,s3c2440-i2c", .data = (void *)TYPE_S3C2440 },
>> {},
>> };
>> MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
>> -#else
>> -#define s3c24xx_i2c_match NULL
>> #endif
>>
>> static struct platform_driver s3c24xx_i2c_driver = {
>> @@ -1140,7 +1124,7 @@ static struct platform_driver s3c24xx_i2c_driver = {
>> .owner = THIS_MODULE,
>> .name = "s3c-i2c",
>> .pm = S3C24XX_DEV_PM_OPS,
>> - .of_match_table = s3c24xx_i2c_match,
>> + .of_match_table = of_match_ptr(s3c24xx_i2c_match),
>
> Should this change be a separate patch?

Ok, I'll move this part to another patch.

Thanks for review!
--
Karol Lewandowski | Samsung Poland R&D Center | Linux/Platform