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author | Bjorn Andersson <bjorn.andersson@linaro.org> | 2017-08-14 15:46:18 -0700 |
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committer | Andy Gross <andy.gross@linaro.org> | 2017-10-11 23:48:27 -0500 |
commit | 8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a (patch) | |
tree | 8d9823b880adb03cdf422d6773c720b79c6233e5 /drivers/firmware/qcom_scm.c | |
parent | 4e659dbe2d02a56ca0df25c77e099760252a329c (diff) | |
download | linux-stable-8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a.tar.gz linux-stable-8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a.tar.bz2 linux-stable-8c1b7dc9ba2294c6dbd1870a3d2e534bfda3047a.zip |
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.c | 75 |
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) |