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SubjectRe: [PATCH v7 2/2] mfd: syscon: Add hardware spinlock support
Arnd,

> Some system control registers need hardware spinlock to synchronize
> between the multiple subsystems, so we should add hardware spinlock
> support for syscon.
>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> Acked-by: Rob Herring <robh@kernel.org>

... did you sign off on this in the end?

> ---
> Changes since v6:
> - Treat hwlock id 0 as valid for regmap.
>
> Changes since v5:
> - Fix the case that hwspinlock is not enabled.
>
> Changes since v4:
> - Add one exapmle to show how to add hwlock.
> - Fix the coding style issue.
>
> Changes since v3:
> - Add error handling for of_hwspin_lock_get_id()
>
> Changes since v2:
> - Add acked tag from Rob.
>
> Changes since v1:
> - Remove timeout configuration.
> - Modify the binding file to add hwlocks.
> ---
> Documentation/devicetree/bindings/mfd/syscon.txt | 8 ++++++++
> drivers/mfd/syscon.c | 19 +++++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/Documentation/devicetree/bindings/mfd/syscon.txt b/Documentation/devicetree/bindings/mfd/syscon.txt
> index 8b92d45..25d9e9c 100644
> --- a/Documentation/devicetree/bindings/mfd/syscon.txt
> +++ b/Documentation/devicetree/bindings/mfd/syscon.txt
> @@ -16,9 +16,17 @@ Required properties:
> Optional property:
> - reg-io-width: the size (in bytes) of the IO accesses that should be
> performed on the device.
> +- hwlocks: reference to a phandle of a hardware spinlock provider node.
>
> Examples:
> gpr: iomuxc-gpr@20e0000 {
> compatible = "fsl,imx6q-iomuxc-gpr", "syscon";
> reg = <0x020e0000 0x38>;
> + hwlocks = <&hwlock1 1>;
> +};
> +
> +hwlock1: hwspinlock@40500000 {
> + ...
> + reg = <0x40500000 0x1000>;
> + #hwlock-cells = <1>;
> };
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index b93fe4c..7eaa40b 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -13,6 +13,7 @@
> */
>
> #include <linux/err.h>
> +#include <linux/hwspinlock.h>
> #include <linux/io.h>
> #include <linux/module.h>
> #include <linux/list.h>
> @@ -87,6 +88,24 @@ static struct syscon *of_syscon_register(struct device_node *np)
> if (ret)
> reg_io_width = 4;
>
> + ret = of_hwspin_lock_get_id(np, 0);
> + if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
> + syscon_config.use_hwlock = true;
> + syscon_config.hwlock_id = ret;
> + syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
> + } else if (ret < 0) {
> + switch (ret) {
> + case -ENOENT:
> + /* Ignore missing hwlock, it's optional. */
> + break;
> + default:
> + pr_err("Failed to retrieve valid hwlock: %d\n", ret);
> + /* fall-through */
> + case -EPROBE_DEFER:
> + goto err_regmap;
> + }
> + }
> +
> syscon_config.reg_stride = reg_io_width;
> syscon_config.val_bits = reg_io_width * 8;
> syscon_config.max_register = resource_size(&res) - reg_io_width;

--
Lee Jones
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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