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    SubjectRe: [PATCH 2/3] i2c-s3c2410: Rework device type handling
    Hi,

    On Wed, Mar 21, 2012 at 08:11:52PM +0100, Karol Lewandowski 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 unsigned int that holds
    > bitmask with revision-specific quirks
    >
    > Signed-off-by: Karol Lewandowski <k.lewandowsk@samsung.com>
    > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

    Okay, so this driver needs to the 'data' field from either
    platform_device_id or of_device_id and implements a function for that,
    namely s3c24xx_get_device_quirks(). Grant, Rob: I'd think there might be
    more drivers in need of that, so maybe it makes sense to have a generic
    of-helper function?

    > ---
    > drivers/i2c/busses/i2c-s3c2410.c | 47 ++++++++++++++++++-------------------
    > 1 files changed, 23 insertions(+), 24 deletions(-)
    >
    > diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
    > index 85e3664..f7b6a14 100644
    > --- a/drivers/i2c/busses/i2c-s3c2410.c
    > +++ b/drivers/i2c/busses/i2c-s3c2410.c
    > @@ -44,8 +44,14 @@
    > #include <plat/regs-iic.h>
    > #include <plat/iic.h>
    >
    > -/* i2c controller state */
    > +#ifdef CONFIG_OF
    > +static const struct of_device_id s3c24xx_i2c_match[];
    > +#endif

    Uh, forward declaration with #ifdef. I'd think we should get this simply
    to the front.

    > dd
    > +/* Treat S3C2410 as baseline hardware, anything else is supported via quirks */
    > +#define QUIRK_S3C2440 (1 << 0)

    Minor: Is it really a quirk being s3c2440? Maybe FLAG_*, dunno.

    > +
    > +/* i2c controller state */
    > enum s3c24xx_i2c_state {
    > STATE_IDLE,
    > STATE_START,
    > @@ -54,14 +60,10 @@ 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 quirks;
    > unsigned int suspended:1;
    >
    > struct i2c_msg *msg;
    > @@ -88,26 +90,22 @@ struct s3c24xx_i2c {
    > #endif
    > };
    >
    > -/* default platform data removed, dev should always carry data. */
    > -
    > -/* s3c24xx_i2c_is2440()
    > +/* s3c24xx_get_device_quirks
    > *
    > - * return true is this is an s3c2440
    > + * Get controller type either from device tree or platform device variant.
    > */
    >
    > -static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
    > +static inline unsigned int s3c24xx_get_device_quirks(struct platform_device *pdev)
    > {
    > - 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");
    > + if (pdev->dev.of_node) {
    > + const struct of_device_id *match;
    > + match = of_match_node(&s3c24xx_i2c_match[0], pdev->dev.of_node);

    Minor: I think it is more readable to drop the [0]

    > + return (unsigned int)match->data;
    > + }
    > #endif
    >
    > - type = platform_get_device_id(pdev)->driver_data;
    > - return type == TYPE_S3C2440;
    > + return platform_get_device_id(pdev)->driver_data;
    > }
    >
    > /* s3c24xx_i2c_master_complete
    > @@ -676,7 +674,7 @@ 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->quirks & QUIRK_S3C2440) {
    > unsigned long sda_delay;
    >
    > if (pdata->sda_delay) {
    > @@ -906,6 +904,7 @@ static int s3c24xx_i2c_probe(struct platform_device *pdev)
    > goto err_noclk;
    > }
    >
    > + i2c->quirks = s3c24xx_get_device_quirks(pdev);
    > if (pdata)
    > memcpy(i2c->pdata, pdata, sizeof(*pdata));
    > else
    > @@ -1113,18 +1112,18 @@ static const struct dev_pm_ops s3c24xx_i2c_dev_pm_ops = {
    > static struct platform_device_id s3c24xx_driver_ids[] = {
    > {
    > .name = "s3c2410-i2c",
    > - .driver_data = TYPE_S3C2410,
    > + .driver_data = 0,
    > }, {
    > .name = "s3c2440-i2c",
    > - .driver_data = TYPE_S3C2440,
    > + .driver_data = QUIRK_S3C2440,
    > }, { },
    > };
    > 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 *)0 },
    > + { .compatible = "samsung,s3c2440-i2c", .data = (void *)QUIRK_S3C2440 },

    Hmm, the need to sepcify the quirks twice may lead to only one instance
    being updated in future patches, but I don't see a way around that,
    currently :(

    > {},
    > };
    > MODULE_DEVICE_TABLE(of, s3c24xx_i2c_match);
    > --
    > 1.7.9
    >

    Thanks,

    Wolfram

    --
    Pengutronix e.K. | Wolfram Sang |
    Industrial Linux Solutions | http://www.pengutronix.de/ |
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