From: Mikko Perttunen <mperttunen@xxxxxxxxxx>
On Tegra210 systems with new enough boot software, direct register
accesses to PMC register space from the non-secure world are not
allowed. Instead a monitor call may be used to read and write PMC
registers.
Add code to detect such a system by attempting to write a scratch
register and detecting if the write happened or not. If not, we switch
to doing all register accesses through the monitor call.
Signed-off-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/soc/tegra/pmc.c | 100 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 97 insertions(+), 3 deletions(-)
diff --git a/drivers/soc/tegra/pmc.c b/drivers/soc/tegra/pmc.c
index 976f93628fff..8628a2a17ebb 100644
--- a/drivers/soc/tegra/pmc.c
+++ b/drivers/soc/tegra/pmc.c
@@ -20,6 +20,7 @@
#define pr_fmt(fmt) "tegra-pmc: " fmt
+#include <linux/arm-smccc.h>
#include <linux/clk.h>
#include <linux/clk/tegra.h>
#include <linux/debugfs.h>
@@ -145,6 +146,11 @@
#define WAKE_AOWAKE_CTRL 0x4f4
#define WAKE_AOWAKE_CTRL_INTR_POLARITY BIT(0)
+/* for secure PMC */
+#define TEGRA_SMC_PMC 0xc2fffe00
+#define TEGRA_SMC_PMC_READ 0xaa
+#define TEGRA_SMC_PMC_WRITE 0xbb
+
struct tegra_powergate {
struct generic_pm_domain genpd;
struct tegra_pmc *pmc;
@@ -216,6 +222,7 @@ struct tegra_pmc_soc {
bool has_gpu_clamps;
bool needs_mbist_war;
bool has_impl_33v_pwr;
+ bool maybe_tz_only;
const struct tegra_io_pad_soc *io_pads;
unsigned int num_io_pads;
@@ -278,6 +285,7 @@ static const char * const tegra30_reset_sources[] = {
* @scratch: pointer to I/O remapped region for scratch registers
* @clk: pointer to pclk clock
* @soc: pointer to SoC data structure
+ * @tz_only: flag specifying if the PMC can only be accessed via TrustZone
* @debugfs: pointer to debugfs entry
* @rate: currently configured rate of pclk
* @suspend_mode: lowest suspend mode available
@@ -308,6 +316,7 @@ struct tegra_pmc {
struct dentry *debugfs;
const struct tegra_pmc_soc *soc;
+ bool tz_only;
unsigned long rate;
@@ -346,13 +355,62 @@ to_powergate(struct generic_pm_domain *domain)
static u32 tegra_pmc_readl(struct tegra_pmc *pmc, unsigned long offset)
{
+ struct arm_smccc_res res;
+
+ if (pmc->tz_only) {
+ arm_smccc_smc(TEGRA_SMC_PMC, TEGRA_SMC_PMC_READ, offset, 0, 0,
+ 0, 0, 0, &res);
+ if (res.a0) {
+ if (pmc->dev)
+ dev_warn(pmc->dev, "%s(): SMC failed: %lu\n",
+ __func__, res.a0);
+ else
+ pr_warn("%s(): SMC failed: %lu\n", __func__,
+ res.a0);
+ }
+
+ return res.a1;
+ }
+
return readl(pmc->base + offset);
}
static void tegra_pmc_writel(struct tegra_pmc *pmc, u32 value,
unsigned long offset)
{
- writel(value, pmc->base + offset);
+ struct arm_smccc_res res;
+
+ if (pmc->tz_only) {
+ arm_smccc_smc(TEGRA_SMC_PMC, TEGRA_SMC_PMC_WRITE, offset,
+ value, 0, 0, 0, 0, &res);
+ if (res.a0) {
+ if (pmc->dev)
+ dev_warn(pmc->dev, "%s(): SMC failed: %lu\n",
+ __func__, res.a0);
+ else
+ pr_warn("%s(): SMC failed: %lu\n", __func__,
+ res.a0);
+ }
+ } else {
+ writel(value, pmc->base + offset);
+ }
+}
+
+static u32 tegra_pmc_scratch_readl(struct tegra_pmc *pmc, unsigned long offset)
+{
+ if (pmc->tz_only)
+ return tegra_pmc_readl(pmc, offset);
+
+ return readl(pmc->scratch + offset);
+}
+
+static void tegra_pmc_scratch_writel(struct tegra_pmc *pmc, u32 value,
+ unsigned long offset)
+{
+ if (pmc->tz_only)
+ tegra_pmc_writel(pmc, value, offset);
+ else
+ writel(value, pmc->scratch + offset);
}
/*
@@ -776,7 +834,7 @@ static int tegra_pmc_restart_notify(struct notifier_block *this,
const char *cmd = data;
u32 value;
- value = readl(pmc->scratch + pmc->soc->regs->scratch0);
+ value = tegra_pmc_scratch_readl(pmc, pmc->soc->regs->scratch0);
value &= ~PMC_SCRATCH0_MODE_MASK;
if (cmd) {
@@ -790,7 +848,7 @@ static int tegra_pmc_restart_notify(struct notifier_block *this,
value |= PMC_SCRATCH0_MODE_RCM;
}
- writel(value, pmc->scratch + pmc->soc->regs->scratch0);
+ tegra_pmc_scratch_writel(pmc, value, pmc->soc->regs->scratch0);
/* reset everything but PMC_SCRATCH0 and PMC_RST_STATUS */
value = tegra_pmc_readl(pmc, PMC_CNTRL);
@@ -2071,6 +2129,7 @@ static const struct tegra_pmc_soc tegra20_pmc_soc = {
.has_gpu_clamps = false,
.needs_mbist_war = false,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = false,
.num_io_pads = 0,
.io_pads = NULL,
.num_pin_descs = 0,
@@ -2117,6 +2176,7 @@ static const struct tegra_pmc_soc tegra30_pmc_soc = {
.has_gpu_clamps = false,
.needs_mbist_war = false,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = false,
.num_io_pads = 0,
.io_pads = NULL,
.num_pin_descs = 0,
@@ -2167,6 +2227,7 @@ static const struct tegra_pmc_soc tegra114_pmc_soc = {
.has_gpu_clamps = false,
.needs_mbist_war = false,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = false,
.num_io_pads = 0,
.io_pads = NULL,
.num_pin_descs = 0,
@@ -2277,6 +2338,7 @@ static const struct tegra_pmc_soc tegra124_pmc_soc = {
.has_gpu_clamps = true,
.needs_mbist_war = false,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = false,
.num_io_pads = ARRAY_SIZE(tegra124_io_pads),
.io_pads = tegra124_io_pads,
.num_pin_descs = ARRAY_SIZE(tegra124_pin_descs),
@@ -2382,6 +2444,7 @@ static const struct tegra_pmc_soc tegra210_pmc_soc = {
.has_gpu_clamps = true,
.needs_mbist_war = true,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = true,
.num_io_pads = ARRAY_SIZE(tegra210_io_pads),
.io_pads = tegra210_io_pads,
.num_pin_descs = ARRAY_SIZE(tegra210_pin_descs),
@@ -2506,6 +2569,7 @@ static const struct tegra_pmc_soc tegra186_pmc_soc = {
.has_gpu_clamps = false,
.needs_mbist_war = false,
.has_impl_33v_pwr = true,
+ .maybe_tz_only = false,
.num_io_pads = ARRAY_SIZE(tegra186_io_pads),
.io_pads = tegra186_io_pads,
.num_pin_descs = ARRAY_SIZE(tegra186_pin_descs),
@@ -2585,6 +2649,7 @@ static const struct tegra_pmc_soc tegra194_pmc_soc = {
.has_gpu_clamps = false,
.needs_mbist_war = false,
.has_impl_33v_pwr = false,
+ .maybe_tz_only = false,
.num_io_pads = ARRAY_SIZE(tegra194_io_pads),
.io_pads = tegra194_io_pads,
.regs = &tegra186_pmc_regs,
@@ -2619,6 +2684,32 @@ static struct platform_driver tegra_pmc_driver = {
};
builtin_platform_driver(tegra_pmc_driver);
+static bool __init tegra_pmc_detect_tz_only(struct tegra_pmc *pmc)
+{
+ u32 value, saved;
+
+ saved = readl(pmc->base + pmc->soc->regs->scratch0);
+ value = saved ^ 0xffffffff;
+
+ if (value == 0xffffffff)
+ value = 0xdeadbeef;
+
+ /* write pattern and read it back */
+ writel(value, pmc->base + pmc->soc->regs->scratch0);
+ value = readl(pmc->base + pmc->soc->regs->scratch0);
+
+ /* if we read all-zeroes, access is restricted to TZ only */
+ if (value == 0) {
+ pr_info("access to PMC is restricted to TZ\n");
+ return true;
+ }
+
+ /* restore original value */
+ writel(saved, pmc->base + pmc->soc->regs->scratch0);
+
+ return false;
+}
+
/*
* Early initialization to allow access to registers in the very early boot
* process.
@@ -2681,6 +2772,9 @@ static int __init tegra_pmc_early_init(void)
if (np) {
pmc->soc = match->data;
+ if (pmc->soc->maybe_tz_only)
+ pmc->tz_only = tegra_pmc_detect_tz_only(pmc);
+
tegra_powergate_init(pmc, np);
/*
--
2.19.1
