2023-06-28 12:46:20

by Mukesh Ojha

Subject: [PATCH v4 17/21] firmware: qcom_scm: provide a read-modify-write function

It was realized by Srinivas K. that there is a need of
read-modify-write scm exported function so that it can
be used by multiple clients.

Let's introduce qcom_scm_io_update_field() which masks
out the bits and write the passed value to that
bit-offset. Subsequent patch will use this function.

Suggested-by: Srinivas Kandagatla <[email protected]>
Signed-off-by: Mukesh Ojha <[email protected]>
---
drivers/firmware/qcom_scm.c | 15 +++++++++++++++
include/linux/firmware/qcom/qcom_scm.h | 2 ++
2 files changed, 17 insertions(+)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index fde33acd46b7..104d86e49b97 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -407,6 +407,21 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
}
EXPORT_SYMBOL(qcom_scm_set_remote_state);

+int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask, unsigned int val)
+{
+ unsigned int old, new;
+ int ret;
+
+ ret = qcom_scm_io_readl(addr, &old);
+ if (ret)
+ return ret;
+
+ new = (old & ~mask) | (val & mask);
+
+ return qcom_scm_io_writel(addr, new);
+}
+EXPORT_SYMBOL(qcom_scm_io_update_field);
+
static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
{
struct qcom_scm_desc desc = {
diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
index 250ea4efb7cb..ca41e4eb33ad 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -84,6 +84,8 @@ extern bool qcom_scm_pas_supported(u32 peripheral);

extern int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val);
extern int qcom_scm_io_writel(phys_addr_t addr, unsigned int val);
+extern int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask,
+ unsigned int val);

extern bool qcom_scm_restore_sec_cfg_available(void);
extern int qcom_scm_restore_sec_cfg(u32 device_id, u32 spare);
--
2.7.4

2023-06-30 05:21:54

by Pavan Kondeti

Subject: Re: [PATCH v4 17/21] firmware: qcom_scm: provide a read-modify-write function

On Wed, Jun 28, 2023 at 06:04:44PM +0530, Mukesh Ojha wrote:
> It was realized by Srinivas K. that there is a need of
> read-modify-write scm exported function so that it can
> be used by multiple clients.
>
> Let's introduce qcom_scm_io_update_field() which masks
> out the bits and write the passed value to that
> bit-offset. Subsequent patch will use this function.
>
> Suggested-by: Srinivas Kandagatla <[email protected]>
> Signed-off-by: Mukesh Ojha <[email protected]>
> ---
> drivers/firmware/qcom_scm.c | 15 +++++++++++++++
> include/linux/firmware/qcom/qcom_scm.h | 2 ++
> 2 files changed, 17 insertions(+)
>
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index fde33acd46b7..104d86e49b97 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -407,6 +407,21 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
> }
> EXPORT_SYMBOL(qcom_scm_set_remote_state);
>
> +int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask, unsigned int val)
> +{
> + unsigned int old, new;
> + int ret;
> +
> + ret = qcom_scm_io_readl(addr, &old);
> + if (ret)
> + return ret;
> +
> + new = (old & ~mask) | (val & mask);
> +
> + return qcom_scm_io_writel(addr, new);
> +}

I believe this API leaves the atomicity part to the client. or how does
it work?

Thanks,
Pavan