On Mon, Jan 08, 2024 at 08:57:31PM +0530, Mukesh Ojha wrote:
> It was realized by Srinivas K. that there is a need of
"need" is a strong word for this functionality, unless there's some use
case that I'm missing.
> read-modify-write scm exported function so that it can
> be used by multiple clients.
>
> Let's introduce qcom_scm_io_rmw() which masks out the bits
> and write the passed value to that bit-offset.
>
> Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
> Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
> Tested-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx> # IPQ9574 and IPQ5332
> ---
> drivers/firmware/qcom/qcom_scm.c | 26 ++++++++++++++++++++++++++
> include/linux/firmware/qcom/qcom_scm.h | 1 +
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
> index 520de9b5633a..25549178a30f 100644
> --- a/drivers/firmware/qcom/qcom_scm.c
> +++ b/drivers/firmware/qcom/qcom_scm.c
> @@ -19,6 +19,7 @@
> #include <linux/of_irq.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> +#include <linux/spinlock.h>
> #include <linux/reset-controller.h>
> #include <linux/types.h>
>
> @@ -41,6 +42,8 @@ struct qcom_scm {
> int scm_vote_count;
>
> u64 dload_mode_addr;
> + /* Atomic context only */
> + spinlock_t lock;
> };
>
> struct qcom_scm_current_perm_info {
> @@ -481,6 +484,28 @@ static int qcom_scm_disable_sdi(void)
> return ret ? : res.result[0];
> }
>
> +int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val)
> +{
> + unsigned int old, new;
> + int ret;
> +
> + if (!__scm)
> + return -EINVAL;
> +
> + spin_lock(&__scm->lock);
Please express that this lock is just for create mutual exclusion
between rmw operations, nothing else.
Also please make a statement why this is desirable and/or needed.
Regards,
Bjorn
> + ret = qcom_scm_io_readl(addr, &old);
> + if (ret)
> + goto unlock;
> +
> + new = (old & ~mask) | (val & mask);
> +
> + ret = qcom_scm_io_writel(addr, new);
> +unlock:
> + spin_unlock(&__scm->lock);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(qcom_scm_io_rmw);
> +
> static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
> {
> struct qcom_scm_desc desc = {
> @@ -1824,6 +1849,7 @@ static int qcom_scm_probe(struct platform_device *pdev)
> return ret;
>
> mutex_init(&scm->scm_bw_lock);
> + spin_lock_init(&scm->lock);
>
> scm->path = devm_of_icc_get(&pdev->dev, NULL);
> if (IS_ERR(scm->path))
> diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
> index ccaf28846054..3a8bb2e603b3 100644
> --- a/include/linux/firmware/qcom/qcom_scm.h
> +++ b/include/linux/firmware/qcom/qcom_scm.h
> @@ -82,6 +82,7 @@ bool qcom_scm_pas_supported(u32 peripheral);
>
> int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val);
> int qcom_scm_io_writel(phys_addr_t addr, unsigned int val);
> +int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val);
>
> bool qcom_scm_restore_sec_cfg_available(void);
> int qcom_scm_restore_sec_cfg(u32 device_id, u32 spare);
> --
> 2.7.4
>
