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Message-ID: <86391f5a-ccbc-133b-47d2-2d98e40d7ef7@linaro.org>
Date: Wed, 8 Mar 2023 15:06:29 +0000
From: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
To: Mukesh Ojha <quic_mojha@...cinc.com>, agross@...nel.org,
andersson@...nel.org, konrad.dybcio@...aro.org
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/4] firmware: scm: Modify only the DLOAD bit in TCSR
register for download mode
On 01/03/2023 09:55, Mukesh Ojha wrote:
> CrashDump collection is based on the DLOAD bit of TCSR register.
> To retain other bits, we read the register and modify only the
> DLOAD bit as the other bits have their own significance.
>
> Originally-by: Poovendhan Selvaraj <quic_poovendh@...cinc.com>
> Signed-off-by: Mukesh Ojha <quic_mojha@...cinc.com>
> ---
> Changes in v2:
> - Addressed comment made by Bjorn.
> - Added download mask from patch 3 to this.
>
> drivers/firmware/qcom_scm.c | 17 +++++++++++++++--
> 1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index 51eb853..c9f1fad 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -27,6 +27,8 @@ module_param(download_mode, bool, 0);
> #define SCM_HAS_IFACE_CLK BIT(1)
> #define SCM_HAS_BUS_CLK BIT(2)
>
> +#define QCOM_DOWNLOAD_MODE_MASK 0x30
> +
> struct qcom_scm {
> struct device *dev;
> struct clk *core_clk;
> @@ -419,6 +421,7 @@ static void qcom_scm_set_download_mode(bool enable)
> {
> bool avail;
> int ret = 0;
> + u32 val;
>
> avail = __qcom_scm_is_call_available(__scm->dev,
> QCOM_SCM_SVC_BOOT,
> @@ -426,8 +429,18 @@ static void qcom_scm_set_download_mode(bool enable)
> if (avail) {
> ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
> } else if (__scm->dload_mode_addr) {
> - ret = qcom_scm_io_writel(__scm->dload_mode_addr,
> - enable ? QCOM_SCM_BOOT_SET_DLOAD_MODE : 0);
> + ret = qcom_scm_io_readl(__scm->dload_mode_addr, &val);
> + if (ret) {
> + dev_err(__scm->dev,
> + "failed to read dload mode address value: %d\n", ret);
> + return;
> + }
> +
> + val &= ~QCOM_DOWNLOAD_MODE_MASK;
> + if (enable)
> + val |= QCOM_SCM_BOOT_SET_DLOAD_MODE;
> +
> + ret = qcom_scm_io_writel(__scm->dload_mode_addr, val);
This is the second instance of such pattern of usage one is already in
./drivers/pinctrl/qcom/pinctrl-msm.c
I think it makes sense to move setting fields in register to a dedicated
function like this:
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 << ffs(mask) - 1);
return qcom_scm_io_writel(addr, new);
}
EXPORT_SYMBOL(qcom_scm_io_update_field);
then we could use it like this:
ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
QCOM_DOWNLOAD_MODE_MASK, dl_mode)
--srini
> } else {
> dev_err(__scm->dev,
> "No available mechanism for setting download mode\n");
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