From:   Mukesh Ojha <quic_mojha@quicinc.com>
To:     <agross@kernel.org>, <andersson@kernel.org>,
        <konrad.dybcio@linaro.org>
CC:     <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        "Mukesh Ojha" <quic_mojha@quicinc.com>
Subject: [PATCH v2 3/4] firmware: qcom_scm: Refactor code to support multiple download mode
Date:   Wed, 1 Mar 2023 15:25:54 +0530
Message-ID: <1677664555-30191-4-git-send-email-quic_mojha@quicinc.com>
In-Reply-To: <1677664555-30191-1-git-send-email-quic_mojha@quicinc.com>
References: <1677664555-30191-1-git-send-email-quic_mojha@quicinc.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

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>
---
Changes in v2:
 - Passed download mode as parameter
 - Accept human accepatable download mode string.
 - enable = !!dload_mode
 - Shifted module param callback to somewhere down in
   the file so that it no longer need to know the
   prototype of qcom_scm_set_download_mode()
 - updated commit text.

 drivers/firmware/Kconfig    | 11 --------
 drivers/firmware/qcom_scm.c | 65 ++++++++++++++++++++++++++++++++++++++-------
 2 files changed, 56 insertions(+), 20 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 c9f1fad..ca07208 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -17,17 +17,22 @@
 #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);
-
 #define SCM_HAS_CORE_CLK	BIT(0)
 #define SCM_HAS_IFACE_CLK	BIT(1)
 #define SCM_HAS_BUS_CLK		BIT(2)
 
 #define QCOM_DOWNLOAD_MODE_MASK 0x30
+#define QCOM_DOWNLOAD_FULLDUMP	0x10
+#define QCOM_DOWNLOAD_NODUMP	0x0
+
+#define MAX_DLOAD_LEN	8
+
+static char download_mode[] = "off";
+static u32 dload_mode;
 
 struct qcom_scm {
 	struct device *dev;
@@ -417,8 +422,9 @@ 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 dload_mode)
 {
+	bool enable = !!dload_mode;
 	bool avail;
 	int ret = 0;
 	u32 val;
@@ -438,7 +444,7 @@ static void qcom_scm_set_download_mode(bool enable)
 
 		val &= ~QCOM_DOWNLOAD_MODE_MASK;
 		if (enable)
-			val |= QCOM_SCM_BOOT_SET_DLOAD_MODE;
+			val |= dload_mode;
 
 		ret = qcom_scm_io_writel(__scm->dload_mode_addr, val);
 	} else {
@@ -1338,6 +1344,47 @@ bool qcom_scm_is_available(void)
 }
 EXPORT_SYMBOL(qcom_scm_is_available);
 
+static int set_dload_mode(const char *val, const struct kernel_param *kp)
+{
+	int ret;
+
+	if (!strncmp(val, "full", strlen("full"))) {
+		dload_mode = QCOM_DOWNLOAD_FULLDUMP;
+	} else if (!strncmp(val, "off", strlen("off"))) {
+		dload_mode = QCOM_DOWNLOAD_NODUMP;
+	} else {
+		if (kstrtouint(val, 0, &dload_mode) ||
+		     !(dload_mode == 0 || dload_mode == 1)) {
+			pr_err("unknown download mode\n");
+			return -EINVAL;
+		}
+
+	}
+
+	ret = param_set_copystring(val, kp);
+	if (ret)
+		return ret;
+
+	if (__scm)
+		qcom_scm_set_download_mode(dload_mode);
+
+	return 0;
+}
+
+static const struct kernel_param_ops dload_mode_param_ops = {
+	.set = set_dload_mode,
+	.get = param_get_string,
+};
+
+static struct kparam_string dload_mode_param = {
+	.string = download_mode,
+	.maxlen = MAX_DLOAD_LEN,
+};
+
+module_param_cb(download_mode, &dload_mode_param_ops, &dload_mode_param, 0644);
+MODULE_PARM_DESC(download_mode,
+		 "Download mode: off/full or 0/1/off/on for existing users");
+
 static int qcom_scm_probe(struct platform_device *pdev)
 {
 	struct qcom_scm *scm;
@@ -1418,12 +1465,12 @@ 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);
+	if (dload_mode)
+		qcom_scm_set_download_mode(dload_mode);
 
 	return 0;
 }
@@ -1431,7 +1478,7 @@ 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