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SubjectRe: [PATCH] reset: meson: add level reset support for GX SoC family
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On 17/10/2017 12:08, Philipp Zabel wrote:
> Hi Neil,
>
> On Mon, 2017-10-16 at 17:26 +0200, Neil Armstrong wrote:
>> The Amlogic GX SoC family embeds alternate registers to drive the reset
>> levels next to the pulse registers.
>>
>> This patch adds support for level reset handling on the GX family only.
>>
>> The Meson8 family has an alternate way to handle level reset.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>
> thank you for the patch, comments below:
>
>> ---
>> drivers/reset/reset-meson.c | 57 +++++++++++++++++++++++++++++++++++++++++----
>> 1 file changed, 53 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/reset/reset-meson.c b/drivers/reset/reset-meson.c
>> index a8b915e..d55e440 100644
>> --- a/drivers/reset/reset-meson.c
>> +++ b/drivers/reset/reset-meson.c
>> @@ -62,9 +62,11 @@
>> #include <linux/reset-controller.h>
>> #include <linux/slab.h>
>> #include <linux/types.h>
>> +#include <linux/of_device.h>
>>
>> #define REG_COUNT 8
>> #define BITS_PER_REG 32
>> +#define LEVEL_OFFSET 0x7c
>>
>> struct meson_reset {
>> void __iomem *reg_base;
>> @@ -88,18 +90,61 @@ static int meson_reset_reset(struct reset_controller_dev *rcdev,
>> return 0;
>> }
>>
>> -static const struct reset_control_ops meson_reset_ops = {
>> +static int meson_reset_level(struct reset_controller_dev *rcdev,
>> + unsigned long id, bool assert)
>> +{
>> + struct meson_reset *data =
>> + container_of(rcdev, struct meson_reset, rcdev);
>> + unsigned int bank = id / BITS_PER_REG;
>> + unsigned int offset = id % BITS_PER_REG;
>> + void __iomem *reg_addr = data->reg_base + LEVEL_OFFSET + (bank << 2);
>> + u32 reg;
>> +
>> + if (bank >= REG_COUNT)
>> + return -EINVAL;
>
> This check is not necessary. The same check is in meson_reset_reset,
> which I didn't notice last time.
>
> of_reset_simple_xlate, the default rcdev->of_xlate implementation,
> already guarantees id < rcdev->nr_resets. And since nr_resets is set to
> REG_COUNT * BITS_PER_REG, we know that id < REG_COUNT * BITS_PER_REG and
> thus bank <= id / BITS_PER_REG < REG_COUNT.

Ok will remove.

>
>> + reg = readl(reg_addr);
>> + if (assert)
>> + writel(reg & ~BIT(offset), reg_addr);
>> + else
>> + writel(reg | BIT(offset), reg_addr);
>
> These read-modify-write operations must be protected by a spinlock.

Ok will add

>
>> +
>> + return 0;
>> +}
>> +
>> +static int meson_reset_assert(struct reset_controller_dev *rcdev,
>> + unsigned long id)
>> +{
>> + return meson_reset_level(rcdev, id, true);
>> +}
>> +
>> +static int meson_reset_deassert(struct reset_controller_dev *rcdev,
>> + unsigned long id)
>> +{
>> + return meson_reset_level(rcdev, id, false);
>> +}
>> +
>> +static const struct reset_control_ops meson_reset_meson8_ops = {
>> + .reset = meson_reset_reset,
>> +};
>> +
>> +static const struct reset_control_ops meson_reset_gx_ops = {
>> .reset = meson_reset_reset,
>> + .assert = meson_reset_assert,
>> + .deassert = meson_reset_deassert,
>> };
>>
>> static const struct of_device_id meson_reset_dt_ids[] = {
>> - { .compatible = "amlogic,meson8b-reset", },
>> - { .compatible = "amlogic,meson-gxbb-reset", },
>> + { .compatible = "amlogic,meson8b-reset",
>> + .data = (void *) &meson_reset_meson8_ops, },
>> + { .compatible = "amlogic,meson-gxbb-reset",
>> + .data = (void *) &meson_reset_gx_ops, },
>> { /* sentinel */ },
>> };
>
> of_device_id.data ist const void *, so there is no need to cast here.

Ok will remove then

>
>> static int meson_reset_probe(struct platform_device *pdev)
>> {
>> + const struct reset_control_ops *ops;
>> struct meson_reset *data;
>> struct resource *res;
>>
>> @@ -107,6 +152,10 @@ static int meson_reset_probe(struct platform_device *pdev)
>> if (!data)
>> return -ENOMEM;
>>
>> + ops = of_device_get_match_data(&pdev->dev);
>> + if (!ops)
>> + return -EINVAL;
>> +
>> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> data->reg_base = devm_ioremap_resource(&pdev->dev, res);
>> if (IS_ERR(data->reg_base))
>> @@ -116,7 +165,7 @@ static int meson_reset_probe(struct platform_device *pdev)
>>
>> data->rcdev.owner = THIS_MODULE;
>> data->rcdev.nr_resets = REG_COUNT * BITS_PER_REG;
>> - data->rcdev.ops = &meson_reset_ops;
>> + data->rcdev.ops = ops;
>> data->rcdev.of_node = pdev->dev.of_node;
>>
>> return devm_reset_controller_register(&pdev->dev, &data->rcdev);
>
> regards
> Philipp
>

Thanks,
Neil

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