[PATCH v4 4/5] firmware: qcom_scm: Refactor code to support multiple download mode

Mukesh Ojha
2023-03-27T16:43:01Z

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 | 59 +++++++++++++++++++++++++++++++++++++++------
2 files changed, 52 insertions(+), 18 deletions(-)

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index b59e304..ff7e9f3 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 3c6c5e7..0c94429 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -20,11 +20,11 @@
#include <linux/clk.h>
#include <linux/reset-controller.h>
#include <linux/arm-smccc.h>
+#include <linux/kstrtox.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)
@@ -32,6 +32,7 @@ module_param(download_mode, bool, 0);

#define QCOM_DOWNLOAD_MODE_MASK 0x30
#define QCOM_DOWNLOAD_FULLDUMP 0x1
+#define QCOM_DOWNLOAD_NODUMP 0x0

struct qcom_scm {
struct device *dev;
@@ -440,8 +441,9 @@ 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 ret = 0;

@@ -453,7 +455,7 @@ static void qcom_scm_set_download_mode(bool enable)
} else if (__scm->dload_mode_addr) {
ret = qcom_scm_io_update_field(__scm->dload_mode_addr,
QCOM_DOWNLOAD_MODE_MASK,
- enable ? QCOM_DOWNLOAD_FULLDUMP : 0);
+ enable ? download_mode : 0);
} else {
dev_err(__scm->dev,
"No available mechanism for setting download mode\n");
@@ -1419,6 +1421,49 @@ 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)
+{
+ int len = 0;
+
+ if (download_mode == QCOM_DOWNLOAD_FULLDUMP)
+ len = sysfs_emit(buffer, "full\n");
+ else if (download_mode == QCOM_DOWNLOAD_NODUMP)
+ len = sysfs_emit(buffer, "off\n");
+
+ return len;
+}
+
+static int set_download_mode(const char *val, const struct kernel_param *kp)
+{
+ u32 old = download_mode;
+
+ if (!strncmp(val, "full", strlen("full"))) {
+ download_mode = QCOM_DOWNLOAD_FULLDUMP;
+ } else if (!strncmp(val, "off", strlen("off"))) {
+ download_mode = QCOM_DOWNLOAD_NODUMP;
+ } else if (kstrtouint(val, 0, &download_mode) ||
+ !(download_mode == 0 || download_mode == 1)) {
+ download_mode = old;
+ pr_err("unknown download mode\n");
+ return -EINVAL;
+ }
+
+ 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 or 0/1 for existing users");
+
static int qcom_scm_probe(struct platform_device *pdev)
{
struct qcom_scm *scm;
@@ -1512,12 +1557,12 @@ static int qcom_scm_probe(struct platform_device *pdev)
__get_convention();

/*
- * If requested enable "download mode", from this point on warmboot
+ * If "download mode" is requested, from this point on warmboot
* will cause the boot stages to enter download mode, unless
* disabled below by a clean shutdown/reboot.
*/
if (download_mode)
- qcom_scm_set_download_mode(true);
+ qcom_scm_set_download_mode(download_mode);

return 0;
}
@@ -1525,7 +1570,7 @@ static int qcom_scm_probe(struct platform_device *pdev)
static void qcom_scm_shutdown(struct platform_device *pdev)
{
/* Clean shutdown, disable download mode to allow normal restart */
- qcom_scm_set_download_mode(false);
+ qcom_scm_set_download_mode(QCOM_DOWNLOAD_NODUMP);
}

static const struct of_device_id qcom_scm_dt_match[] = {
--
2.7.4