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SubjectRe: [PATCH 1/3] iio: adc: at91_adc: Repair broken platform_data support
On 05/03/14 16:57, Alexandre Belloni wrote:
> Trying to use the at91_adc driver while not using device tree is ending up in a
> kernel crash:
>
> Unable to handle kernel NULL pointer dereference at virtual address 00000004
> [...]
> [<c01f3510>] (at91_adc_probe) from [<c0183828>] (platform_drv_probe+0x18/0x48)
> [<c0183828>] (platform_drv_probe) from [<c01824a4>] (driver_probe_device+0x100/0x218)
> [<c01824a4>] (driver_probe_device) from [<c0182648>] (__driver_attach+0x8c/0x90)
> [<c0182648>] (__driver_attach) from [<c0180de4>] (bus_for_each_dev+0x58/0x88)
> [<c0180de4>] (bus_for_each_dev) from [<c0181c7c>] (bus_add_driver+0xd4/0x1d4)
> [<c0181c7c>] (bus_add_driver) from [<c0182c40>] (driver_register+0x78/0xf4)
> [<c0182c40>] (driver_register) from [<c0008998>] (do_one_initcall+0xe8/0x14c)
> [<c0008998>] (do_one_initcall) from [<c02f0b50>] (kernel_init_freeable+0xec/0x1b4)
> [<c02f0b50>] (kernel_init_freeable) from [<c022acdc>] (kernel_init+0x8/0xe4)
> [<c022acdc>] (kernel_init) from [<c0009670>] (ret_from_fork+0x14/0x24)
>
> This is because the at91_adc_caps structure is mandatory but is not filled when
> using platform_data. Correct that by using an id_table. It ensues that the
> driver will not match "at91_adc" anymore but it was crashing anyway.
>
> Fixes: c46016665fff (iio: at91: ADC start-up time calculation changed since at91sam9x5)
> Cc: stable@vger.kernel.org # v3.13+
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Ouch.

It's late in the cycle so I'll send this on to Greg KH with a note
to say either send it to Linus if he is happy doing so - or send
it early in 3.15, then it'll get picked up for stable.

I'll give it a day or so to see if I the at91 maintainers are happy
with the other two parts as it is probably cleaner if all 3 go together.

Applied to the fixes-togreg branch of iio.git

Thanks,

Jonathan


> ---
> drivers/iio/adc/at91_adc.c | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 5b1aa027c034..bbba014c9939 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -765,14 +765,17 @@ static int at91_adc_probe_pdata(struct at91_adc_state *st,
> if (!pdata)
> return -EINVAL;
>
> + st->caps = (struct at91_adc_caps *)
> + platform_get_device_id(pdev)->driver_data;
> +
> st->use_external = pdata->use_external_triggers;
> st->vref_mv = pdata->vref;
> st->channels_mask = pdata->channels_used;
> - st->num_channels = pdata->num_channels;
> + st->num_channels = st->caps->num_channels;
> st->startup_time = pdata->startup_time;
> st->trigger_number = pdata->trigger_number;
> st->trigger_list = pdata->trigger_list;
> - st->registers = pdata->registers;
> + st->registers = &st->caps->registers;
>
> return 0;
> }
> @@ -1101,7 +1104,6 @@ static int at91_adc_remove(struct platform_device *pdev)
> return 0;
> }
>
> -#ifdef CONFIG_OF
> static struct at91_adc_caps at91sam9260_caps = {
> .calc_startup_ticks = calc_startup_ticks_9260,
> .num_channels = 4,
> @@ -1154,11 +1156,27 @@ static const struct of_device_id at91_adc_dt_ids[] = {
> {},
> };
> MODULE_DEVICE_TABLE(of, at91_adc_dt_ids);
> -#endif
> +
> +static const struct platform_device_id at91_adc_ids[] = {
> + {
> + .name = "at91sam9260-adc",
> + .driver_data = (unsigned long)&at91sam9260_caps,
> + }, {
> + .name = "at91sam9g45-adc",
> + .driver_data = (unsigned long)&at91sam9g45_caps,
> + }, {
> + .name = "at91sam9x5-adc",
> + .driver_data = (unsigned long)&at91sam9x5_caps,
> + }, {
> + /* terminator */
> + }
> +};
> +MODULE_DEVICE_TABLE(platform, at91_adc_ids);
>
> static struct platform_driver at91_adc_driver = {
> .probe = at91_adc_probe,
> .remove = at91_adc_remove,
> + .id_table = at91_adc_ids,
> .driver = {
> .name = DRIVER_NAME,
> .of_match_table = of_match_ptr(at91_adc_dt_ids),
>



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