Re: [PATCH v4 20/21] firmware: qcom_scm: Refactor code to support multiple download mode

Pavan Kondeti
2023-06-30T05:26:19Z

On Wed, Jun 28, 2023 at 06:04:47PM +0530, Mukesh Ojha wrote:
> Currently on Qualcomm SoC, download_mode is enabled if
> CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT is selected.
>
> Refactor the code such that it supports multiple download
> modes and drop CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT config
> instead, give interface to set the download mode from
> module parameter.
>
> Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
> ---
> drivers/firmware/Kconfig | 11 ---------
> drivers/firmware/qcom_scm.c | 56 +++++++++++++++++++++++++++++++++++++++------
> 2 files changed, 49 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index b59e3041fd62..ff7e9f330559 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -215,17 +215,6 @@ config MTK_ADSP_IPC
> config QCOM_SCM
> tristate
>
> -config QCOM_SCM_DOWNLOAD_MODE_DEFAULT
> - bool "Qualcomm download mode enabled by default"
> - depends on QCOM_SCM
> - help
> - A device with "download mode" enabled will upon an unexpected
> - warm-restart enter a special debug mode that allows the user to
> - "download" memory content over USB for offline postmortem analysis.
> - The feature can be enabled/disabled on the kernel command line.
> -
> - Say Y here to enable "download mode" by default.
> -
> config SYSFB
> bool
> select BOOT_VESA_SUPPORT
> diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
> index a9ff77d16c42..946cb0f76a17 100644
> --- a/drivers/firmware/qcom_scm.c
> +++ b/drivers/firmware/qcom_scm.c
> @@ -18,13 +18,13 @@
> #include <linux/of_irq.h>
> #include <linux/of_platform.h>
> #include <linux/clk.h>
> +#include <linux/kstrtox.h>
> #include <linux/reset-controller.h>
> #include <linux/arm-smccc.h>
>
> #include "qcom_scm.h"
>
> -static bool download_mode = IS_ENABLED(CONFIG_QCOM_SCM_DOWNLOAD_MODE_DEFAULT);
> -module_param(download_mode, bool, 0);
> +static u32 download_mode;
>
> #define SCM_HAS_CORE_CLK BIT(0)
> #define SCM_HAS_IFACE_CLK BIT(1)
> @@ -82,6 +82,11 @@ static const char * const qcom_scm_convention_names[] = {
> [SMC_CONVENTION_LEGACY] = "smc legacy",
> };
>
> +static const char * const download_mode_name[] = {
> + [QCOM_DOWNLOAD_NODUMP] = "off",
> + [QCOM_DOWNLOAD_FULLDUMP] = "full",
> +};
> +
> static struct qcom_scm *__scm;
>
> static int qcom_scm_clk_enable(void)
> @@ -442,8 +447,9 @@ static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
> return qcom_scm_call_atomic(__scm->dev, &desc, NULL);
> }
>
> -static void qcom_scm_set_download_mode(bool enable)
> +static void qcom_scm_set_download_mode(u32 download_mode)
> {
> + bool enable = !!download_mode;
> bool avail;
> int val;
> int ret = 0;
> @@ -454,7 +460,7 @@ 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) {
> - val = (enable ? QCOM_DOWNLOAD_FULLDUMP : QCOM_DOWNLOAD_NODUMP);
> + val = download_mode;
> val <<= QCOM_DOWNLOAD_MODE_SHIFT;
> ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
> QCOM_DOWNLOAD_MODE_MASK, val);
> @@ -1425,6 +1431,42 @@ static irqreturn_t qcom_scm_irq_handler(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +static int get_download_mode(char *buffer, const struct kernel_param *kp)
> +{
> + if (download_mode >= ARRAY_SIZE(download_mode_name))
> + return sysfs_emit(buffer, "unknown mode\n");
> +
> + return sysfs_emit(buffer, "%s\n", download_mode_name[download_mode]);
> +}
> +
> +static int set_download_mode(const char *val, const struct kernel_param *kp)
> +{
> + u32 old = download_mode;
> + int ret;
> +
> + ret = sysfs_match_string(download_mode_name, val);
> + if (ret < 0) {
> + download_mode = old;
> + pr_err("qcom_scm: unknown download mode: %s\n", val);
> + return -EINVAL;
> + }

minor nit: %s/-EINVAL/ret

> +
> + download_mode = ret;
> + if (__scm)
> + qcom_scm_set_download_mode(download_mode);
> +
> + return 0;
> +}
> +
> +static const struct kernel_param_ops download_mode_param_ops = {
> + .get = get_download_mode,
> + .set = set_download_mode,
> +};
> +
> +module_param_cb(download_mode, &download_mode_param_ops, NULL, 0644);
> +MODULE_PARM_DESC(download_mode,
> + "download mode: off/full are acceptable values");
> +

Since we are adding a sysfs file under /sys/module/qcom_scm/ , does it
need to be documented under ABI?

Thanks,
Pavan