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authorBjorn Andersson <bjorn.andersson@linaro.org>2017-08-15 01:46:18 +0300
committerAndy Gross <andy.gross@linaro.org>2017-10-12 07:48:27 +0300
commit8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a (patch)
tree8d9823b880adb03cdf422d6773c720b79c6233e5 /drivers/firmware/qcom_scm.c
parent4e659dbe2d02a56ca0df25c77e099760252a329c (diff)
downloadlinux-8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a.tar.xz
firmware: qcom: scm: Expose download-mode control
In order to aid post-mortem debugging the Qualcomm platforms provide a "memory download mode", where the boot loader will provide an interface for custom tools to "download" the content of RAM to a host machine. The mode is triggered by writing a magic value somewhere in RAM, that is read in the boot code path after a warm-restart. Two mechanism for setting this magic value are supported in modern platforms; a direct SCM call to enable the mode or through a secure io write of a magic value. In order for a normal reboot not to trigger "download mode" the magic must be cleared during a clean reboot. Download mode has to be enabled by including qcom_scm.download_mode=1 on the command line. Reviewed-by: Stephen Boyd <sboyd@codeaurora.org> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org> Signed-off-by: Andy Gross <andy.gross@linaro.org>
Diffstat (limited to 'drivers/firmware/qcom_scm.c')
-rw-r--r--drivers/firmware/qcom_scm.c75
1 files changed, 75 insertions, 0 deletions
diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index e18d63935648..9064e559a01f 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -19,15 +19,20 @@
#include <linux/cpumask.h>
#include <linux/export.h>
#include <linux/dma-mapping.h>
+#include <linux/module.h>
#include <linux/types.h>
#include <linux/qcom_scm.h>
#include <linux/of.h>
+#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/clk.h>
#include <linux/reset-controller.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)
@@ -38,6 +43,8 @@ struct qcom_scm {
struct clk *iface_clk;
struct clk *bus_clk;
struct reset_controller_dev reset;
+
+ u64 dload_mode_addr;
};
static struct qcom_scm *__scm;
@@ -345,6 +352,54 @@ int qcom_scm_io_writel(phys_addr_t addr, unsigned int val)
}
EXPORT_SYMBOL(qcom_scm_io_writel);
+static void qcom_scm_set_download_mode(bool enable)
+{
+ bool avail;
+ int ret = 0;
+
+ avail = __qcom_scm_is_call_available(__scm->dev,
+ QCOM_SCM_SVC_BOOT,
+ QCOM_SCM_SET_DLOAD_MODE);
+ if (avail) {
+ ret = __qcom_scm_set_dload_mode(__scm->dev, enable);
+ } else if (__scm->dload_mode_addr) {
+ ret = __qcom_scm_io_writel(__scm->dev, __scm->dload_mode_addr,
+ enable ? QCOM_SCM_SET_DLOAD_MODE : 0);
+ } else {
+ dev_err(__scm->dev,
+ "No available mechanism for setting download mode\n");
+ }
+
+ if (ret)
+ dev_err(__scm->dev, "failed to set download mode: %d\n", ret);
+}
+
+static int qcom_scm_find_dload_address(struct device *dev, u64 *addr)
+{
+ struct device_node *tcsr;
+ struct device_node *np = dev->of_node;
+ struct resource res;
+ u32 offset;
+ int ret;
+
+ tcsr = of_parse_phandle(np, "qcom,dload-mode", 0);
+ if (!tcsr)
+ return 0;
+
+ ret = of_address_to_resource(tcsr, 0, &res);
+ of_node_put(tcsr);
+ if (ret)
+ return ret;
+
+ ret = of_property_read_u32_index(np, "qcom,dload-mode", 1, &offset);
+ if (ret < 0)
+ return ret;
+
+ *addr = res.start + offset;
+
+ return 0;
+}
+
/**
* qcom_scm_is_available() - Checks if SCM is available
*/
@@ -370,6 +425,10 @@ static int qcom_scm_probe(struct platform_device *pdev)
if (!scm)
return -ENOMEM;
+ ret = qcom_scm_find_dload_address(&pdev->dev, &scm->dload_mode_addr);
+ if (ret < 0)
+ return ret;
+
clks = (unsigned long)of_device_get_match_data(&pdev->dev);
if (clks & SCM_HAS_CORE_CLK) {
scm->core_clk = devm_clk_get(&pdev->dev, "core");
@@ -418,9 +477,24 @@ static int qcom_scm_probe(struct platform_device *pdev)
__qcom_scm_init();
+ /*
+ * If requested enable "download mode", from this point on warmboot
+ * will cause the the boot stages to enter download mode, unless
+ * disabled below by a clean shutdown/reboot.
+ */
+ if (download_mode)
+ qcom_scm_set_download_mode(true);
+
return 0;
}
+static void qcom_scm_shutdown(struct platform_device *pdev)
+{
+ /* Clean shutdown, disable download mode to allow normal restart */
+ if (download_mode)
+ qcom_scm_set_download_mode(false);
+}
+
static const struct of_device_id qcom_scm_dt_match[] = {
{ .compatible = "qcom,scm-apq8064",
/* FIXME: This should have .data = (void *) SCM_HAS_CORE_CLK */
@@ -448,6 +522,7 @@ static struct platform_driver qcom_scm_driver = {
.of_match_table = qcom_scm_dt_match,
},
.probe = qcom_scm_probe,
+ .shutdown = qcom_scm_shutdown,
};
static int __init qcom_scm_init(void)