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Date: Mon, 12 Mar 2012 11:28:16 +0530
From: Thomas Abraham <thomas.abraham@...aro.org>
To: Karol Lewandowski <k.lewandowsk@...sung.com>
Cc: ben-linux@...ff.org, m.szyprowski@...sung.com,
linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
devicetree-discuss@...ts.ozlabs.org,
linux-samsung-soc@...r.kernel.org, t.stanislaws@...sung.com,
Kyungmin Park <kyungmin.park@...sung.com>
Subject: Re: [PATCH 1/2] i2c-s3c2410: Rework device type handling
On 9 March 2012 22:34, Karol Lewandowski <k.lewandowsk@...sung.com> 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@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
> ---
> 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)
> 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);
> + 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).
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?
Thanks,
Thomas.
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