Hi folks,
This is a v6 of the series to add support for protected PMU registers found
on gs101 and derivative SoCs. In v2 and later it was re-worked to be based
on a regmap abstraction that I think leads to a much neater overall
solution.
The advantage of the regmap abstraction is that most leaf drivers that
read/write PMU registers need minimal changes.
Example of Exynos drivers that require PMU register access are:
* watchdog
* usb phy
* mipi phy
* ufs phy
This series has been tested on Pixel 6 Oriole / gs101 (by me), exynos850
(by Sam) and odroid xu3 (exynos 5422) by Alexey. That confirms that both
the regmap mmio parts and regmap SMC parts are working correctly.
The expectation is this series would be merged via Krzysztofs Samsung Exynos
tree.
regards,
Peter
Changes since v5:
- Update kerneldoc comment property -> propname
Changes since v4:
- Use same argument names as in struct regmap_config
- Remove inline keyword and rely on compiler
- Update kerneldoc wording
- property -> propname argument rename
- reverse Xmas tree
- Only call of_node_put() when of_parse_phandle() is called
- Collect tags
Changes since v3:
- Fix PMUALIVE_MASK
- Add TENSOR_ prefix
- clear SET_BITS bits on each loop iteration
- change set_bit to set_bits func name
- Fix some alignment
- Add missing return on dev_err_probe
- Reduce indentation in loop
Changes since v2
- Add select REGMAP to Kconfig
- Add constant for SET/CLEAR bits
- Replace kerneldoc with one line comment
- Fix kerneldoc for EXPORT_SYMBOL_GPL funcs
- remove superfluous extern keyword
- dev_err_probe() on probe error
- shorten regmcfg name
- no compatibles inside probe, use match data
- don't mix declarations with/without initializations
- tensor_sec_reg_read() use mmio to avoid access restrictions
- Collect up Reviewed-by
- const for regmap_config structs
Changes since v1:
- Refactor to use custom regmap to abstract SMC register access (Sam / Guenter)
- Add deferred probing support (Saravana / Krzysztof)
v5 lore: https://lore.kernel.org/all/[email protected]/
v4 lore: https://lore.kernel.org/all/[email protected]/
v3 lore: https://lore.kernel.org/all/[email protected]/
v2 lore: https://lore.kernel.org/lkml/[email protected]/
v1 lore: https://lore.kernel.org/all/[email protected]/
Peter Griffin (2):
soc: samsung: exynos-pmu: Add regmap support for SoCs that protect PMU
regs
watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle() for PMU
regs
drivers/soc/samsung/Kconfig | 1 +
drivers/soc/samsung/exynos-pmu.c | 235 ++++++++++++++++++++++++-
drivers/soc/samsung/exynos-pmu.h | 1 +
drivers/watchdog/Kconfig | 1 -
drivers/watchdog/s3c2410_wdt.c | 8 +-
include/linux/soc/samsung/exynos-pmu.h | 11 +-
6 files changed, 249 insertions(+), 8 deletions(-)
--
2.44.0.rc0.258.g7320e95886-goog
Some Exynos based SoCs like Tensor gs101 protect the PMU registers for
security hardening reasons so that they are only write accessible in el3
via an SMC call.
As most Exynos drivers that need to write PMU registers currently obtain a
regmap via syscon (phys, pinctrl, watchdog). Support for the above usecase
is implemented in this driver using a custom regmap similar to syscon to
handle the SMC call. Platforms that don't secure PMU registers, get a mmio
regmap like before. As regmaps abstract out the underlying register access
changes to the leaf drivers are minimal.
A new API exynos_get_pmu_regmap_by_phandle() is provided for leaf drivers
that currently use syscon_regmap_lookup_by_phandle(). This also handles
deferred probing.
Tested-by: Sam Protsenko <[email protected]>
Tested-by: Alexey Klimov <[email protected]>
Reviewed-by: Sam Protsenko <[email protected]>
Signed-off-by: Peter Griffin <[email protected]>
---
Changes since v5:
- Update kerneldoc comment property -> propname
Changes since v4:
- Use same argument names as in struct regmap_config
- Remove inline keyword and rely on compiler
- Update kerneldoc wording
- property -> propname argument rename
- reverse Xmas tree
- Only call of_node_put() when of_parse_phandle is called
- Collect tags
Changes since v3:
- Fix PMUALIVE_MASK
- Add TENSOR_ prefix
- clear SET_BITS bits on each loop iteration
- change set_bit to set_bits in func name
- Fix some alignment
- Add missing return on dev_err_probe
- Reduce indentation in loop
Changes since v2
- Add select REGMAP to Kconfig
- Add constant for SET/CLEAR bits
- Replace kerneldoc with one line comment
- Fix kerneldoc for EXPORT_SYMBOL_GPL funcs
- remove superfluous extern keyword
- dev_err_probe() on probe error
- shorten regmcfg name
- no compatibles inside probe, use match data
- don't mix declarations with/without initializations
- tensor_sec_reg_read() use mmio to avoid access restrictions
- Collect up Reviewed-by
- const for regmap_config structs
---
drivers/soc/samsung/Kconfig | 1 +
drivers/soc/samsung/exynos-pmu.c | 235 ++++++++++++++++++++++++-
drivers/soc/samsung/exynos-pmu.h | 1 +
include/linux/soc/samsung/exynos-pmu.h | 11 +-
4 files changed, 245 insertions(+), 3 deletions(-)
diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig
index 27ec99af77e3..1a5dfdc978dc 100644
--- a/drivers/soc/samsung/Kconfig
+++ b/drivers/soc/samsung/Kconfig
@@ -42,6 +42,7 @@ config EXYNOS_PMU
depends on ARCH_EXYNOS || ((ARM || ARM64) && COMPILE_TEST)
select EXYNOS_PMU_ARM_DRIVERS if ARM && ARCH_EXYNOS
select MFD_CORE
+ select REGMAP_MMIO
# There is no need to enable these drivers for ARMv8
config EXYNOS_PMU_ARM_DRIVERS
diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index 250537d7cfd6..fd8b6ac06656 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -5,6 +5,7 @@
//
// Exynos - CPU PMU(Power Management Unit) support
+#include <linux/arm-smccc.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/mfd/core.h>
@@ -12,19 +13,134 @@
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/delay.h>
+#include <linux/regmap.h>
#include <linux/soc/samsung/exynos-regs-pmu.h>
#include <linux/soc/samsung/exynos-pmu.h>
#include "exynos-pmu.h"
+#define PMUALIVE_MASK GENMASK(13, 0)
+#define TENSOR_SET_BITS (BIT(15) | BIT(14))
+#define TENSOR_CLR_BITS BIT(15)
+#define TENSOR_SMC_PMU_SEC_REG 0x82000504
+#define TENSOR_PMUREG_READ 0
+#define TENSOR_PMUREG_WRITE 1
+#define TENSOR_PMUREG_RMW 2
+
struct exynos_pmu_context {
struct device *dev;
const struct exynos_pmu_data *pmu_data;
+ struct regmap *pmureg;
};
void __iomem *pmu_base_addr;
static struct exynos_pmu_context *pmu_context;
+/* forward declaration */
+static struct platform_driver exynos_pmu_driver;
+
+/*
+ * Tensor SoCs are configured so that PMU_ALIVE registers can only be written
+ * from EL3, but are still read accessible. As Linux needs to write some of
+ * these registers, the following functions are provided and exposed via
+ * regmap.
+ *
+ * Note: This SMC interface is known to be implemented on gs101 and derivative
+ * SoCs.
+ */
+
+/* Write to a protected PMU register. */
+static int tensor_sec_reg_write(void *context, unsigned int reg,
+ unsigned int val)
+{
+ struct arm_smccc_res res;
+ unsigned long pmu_base = (unsigned long)context;
+
+ arm_smccc_smc(TENSOR_SMC_PMU_SEC_REG, pmu_base + reg,
+ TENSOR_PMUREG_WRITE, val, 0, 0, 0, 0, &res);
+
+ /* returns -EINVAL if access isn't allowed or 0 */
+ if (res.a0)
+ pr_warn("%s(): SMC failed: %d\n", __func__, (int)res.a0);
+
+ return (int)res.a0;
+}
+
+/* Read/Modify/Write a protected PMU register. */
+static int tensor_sec_reg_rmw(void *context, unsigned int reg,
+ unsigned int mask, unsigned int val)
+{
+ struct arm_smccc_res res;
+ unsigned long pmu_base = (unsigned long)context;
+
+ arm_smccc_smc(TENSOR_SMC_PMU_SEC_REG, pmu_base + reg,
+ TENSOR_PMUREG_RMW, mask, val, 0, 0, 0, &res);
+
+ /* returns -EINVAL if access isn't allowed or 0 */
+ if (res.a0)
+ pr_warn("%s(): SMC failed: %d\n", __func__, (int)res.a0);
+
+ return (int)res.a0;
+}
+
+/*
+ * Read a protected PMU register. All PMU registers can be read by Linux.
+ * Note: The SMC read register is not used, as only registers that can be
+ * written are readable via SMC.
+ */
+static int tensor_sec_reg_read(void *context, unsigned int reg,
+ unsigned int *val)
+{
+ *val = pmu_raw_readl(reg);
+ return 0;
+}
+
+/*
+ * For SoCs that have set/clear bit hardware this function can be used when
+ * the PMU register will be accessed by multiple masters.
+ *
+ * For example, to set bits 13:8 in PMU reg offset 0x3e80
+ * tensor_set_bits_atomic(ctx, 0x3e80, 0x3f00, 0x3f00);
+ *
+ * Set bit 8, and clear bits 13:9 PMU reg offset 0x3e80
+ * tensor_set_bits_atomic(0x3e80, 0x100, 0x3f00);
+ */
+static int tensor_set_bits_atomic(void *ctx, unsigned int offset, u32 val,
+ u32 mask)
+{
+ int ret;
+ unsigned int i;
+
+ for (i = 0; i < 32; i++) {
+ if (!(mask & BIT(i)))
+ continue;
+
+ offset &= ~TENSOR_SET_BITS;
+
+ if (val & BIT(i))
+ offset |= TENSOR_SET_BITS;
+ else
+ offset |= TENSOR_CLR_BITS;
+
+ ret = tensor_sec_reg_write(ctx, offset, i);
+ if (ret)
+ return ret;
+ }
+ return ret;
+}
+
+static int tensor_sec_update_bits(void *ctx, unsigned int reg,
+ unsigned int mask, unsigned int val)
+{
+ /*
+ * Use atomic operations for PMU_ALIVE registers (offset 0~0x3FFF)
+ * as the target registers can be accessed by multiple masters.
+ */
+ if (reg > PMUALIVE_MASK)
+ return tensor_sec_reg_rmw(ctx, reg, mask, val);
+
+ return tensor_set_bits_atomic(ctx, reg, val, mask);
+}
void pmu_raw_writel(u32 val, u32 offset)
{
@@ -75,11 +191,41 @@ void exynos_sys_powerdown_conf(enum sys_powerdown mode)
#define exynos_pmu_data_arm_ptr(data) NULL
#endif
+static const struct regmap_config regmap_smccfg = {
+ .name = "pmu_regs",
+ .reg_bits = 32,
+ .reg_stride = 4,
+ .val_bits = 32,
+ .fast_io = true,
+ .use_single_read = true,
+ .use_single_write = true,
+ .reg_read = tensor_sec_reg_read,
+ .reg_write = tensor_sec_reg_write,
+ .reg_update_bits = tensor_sec_update_bits,
+};
+
+static const struct regmap_config regmap_mmiocfg = {
+ .name = "pmu_regs",
+ .reg_bits = 32,
+ .reg_stride = 4,
+ .val_bits = 32,
+ .fast_io = true,
+ .use_single_read = true,
+ .use_single_write = true,
+};
+
+static const struct exynos_pmu_data gs101_pmu_data = {
+ .pmu_secure = true
+};
+
/*
* PMU platform driver and devicetree bindings.
*/
static const struct of_device_id exynos_pmu_of_device_ids[] = {
{
+ .compatible = "google,gs101-pmu",
+ .data = &gs101_pmu_data,
+ }, {
.compatible = "samsung,exynos3250-pmu",
.data = exynos_pmu_data_arm_ptr(exynos3250_pmu_data),
}, {
@@ -113,19 +259,75 @@ static const struct mfd_cell exynos_pmu_devs[] = {
{ .name = "exynos-clkout", },
};
+/**
+ * exynos_get_pmu_regmap() - Obtain pmureg regmap
+ *
+ * Find the pmureg regmap previously configured in probe() and return regmap
+ * pointer.
+ *
+ * Return: A pointer to regmap if found or ERR_PTR error value.
+ */
struct regmap *exynos_get_pmu_regmap(void)
{
struct device_node *np = of_find_matching_node(NULL,
exynos_pmu_of_device_ids);
if (np)
- return syscon_node_to_regmap(np);
+ return exynos_get_pmu_regmap_by_phandle(np, NULL);
return ERR_PTR(-ENODEV);
}
EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap);
+/**
+ * exynos_get_pmu_regmap_by_phandle() - Obtain pmureg regmap via phandle
+ * @np: Device node holding PMU phandle property
+ * @propname: Name of property holding phandle value
+ *
+ * Find the pmureg regmap previously configured in probe() and return regmap
+ * pointer.
+ *
+ * Return: A pointer to regmap if found or ERR_PTR error value.
+ */
+struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
+ const char *propname)
+{
+ struct exynos_pmu_context *ctx;
+ struct device_node *pmu_np;
+ struct device *dev;
+
+ if (propname)
+ pmu_np = of_parse_phandle(np, propname, 0);
+ else
+ pmu_np = np;
+
+ if (!pmu_np)
+ return ERR_PTR(-ENODEV);
+
+ /*
+ * Determine if exynos-pmu device has probed and therefore regmap
+ * has been created and can be returned to the caller. Otherwise we
+ * return -EPROBE_DEFER.
+ */
+ dev = driver_find_device_by_of_node(&exynos_pmu_driver.driver,
+ (void *)pmu_np);
+
+ if (propname)
+ of_node_put(pmu_np);
+
+ if (!dev)
+ return ERR_PTR(-EPROBE_DEFER);
+
+ ctx = dev_get_drvdata(dev);
+
+ return ctx->pmureg;
+}
+EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
+
static int exynos_pmu_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
+ struct regmap_config pmu_regmcfg;
+ struct regmap *regmap;
+ struct resource *res;
int ret;
pmu_base_addr = devm_platform_ioremap_resource(pdev, 0);
@@ -137,9 +339,38 @@ static int exynos_pmu_probe(struct platform_device *pdev)
GFP_KERNEL);
if (!pmu_context)
return -ENOMEM;
- pmu_context->dev = dev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENODEV;
+
pmu_context->pmu_data = of_device_get_match_data(dev);
+ /* For SoCs that secure PMU register writes use custom regmap */
+ if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_secure) {
+ pmu_regmcfg = regmap_smccfg;
+ pmu_regmcfg.max_register = resource_size(res) -
+ pmu_regmcfg.reg_stride;
+ /* Need physical address for SMC call */
+ regmap = devm_regmap_init(dev, NULL,
+ (void *)(uintptr_t)res->start,
+ &pmu_regmcfg);
+ } else {
+ /* All other SoCs use a MMIO regmap */
+ pmu_regmcfg = regmap_mmiocfg;
+ pmu_regmcfg.max_register = resource_size(res) -
+ pmu_regmcfg.reg_stride;
+ regmap = devm_regmap_init_mmio(dev, pmu_base_addr,
+ &pmu_regmcfg);
+ }
+
+ if (IS_ERR(regmap))
+ return dev_err_probe(&pdev->dev, PTR_ERR(regmap),
+ "regmap init failed\n");
+
+ pmu_context->pmureg = regmap;
+ pmu_context->dev = dev;
+
if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_init)
pmu_context->pmu_data->pmu_init();
diff --git a/drivers/soc/samsung/exynos-pmu.h b/drivers/soc/samsung/exynos-pmu.h
index 1c652ffd79b4..0a49a2c9a08e 100644
--- a/drivers/soc/samsung/exynos-pmu.h
+++ b/drivers/soc/samsung/exynos-pmu.h
@@ -21,6 +21,7 @@ struct exynos_pmu_conf {
struct exynos_pmu_data {
const struct exynos_pmu_conf *pmu_config;
const struct exynos_pmu_conf *pmu_config_extra;
+ bool pmu_secure;
void (*pmu_init)(void);
void (*powerdown_conf)(enum sys_powerdown);
diff --git a/include/linux/soc/samsung/exynos-pmu.h b/include/linux/soc/samsung/exynos-pmu.h
index a4f5516cc956..2bd9d12d9a52 100644
--- a/include/linux/soc/samsung/exynos-pmu.h
+++ b/include/linux/soc/samsung/exynos-pmu.h
@@ -10,6 +10,7 @@
#define __LINUX_SOC_EXYNOS_PMU_H
struct regmap;
+struct device_node;
enum sys_powerdown {
SYS_AFTR,
@@ -20,12 +21,20 @@ enum sys_powerdown {
extern void exynos_sys_powerdown_conf(enum sys_powerdown mode);
#ifdef CONFIG_EXYNOS_PMU
-extern struct regmap *exynos_get_pmu_regmap(void);
+struct regmap *exynos_get_pmu_regmap(void);
+struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
+ const char *propname);
#else
static inline struct regmap *exynos_get_pmu_regmap(void)
{
return ERR_PTR(-ENODEV);
}
+
+static inline struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
+ const char *propname)
+{
+ return ERR_PTR(-ENODEV);
+}
#endif
#endif /* __LINUX_SOC_EXYNOS_PMU_H */
--
2.44.0.rc0.258.g7320e95886-goog
Obtain the PMU regmap using the new API added to exynos-pmu driver rather
than syscon_regmap_lookup_by_phandle(). As this driver no longer depends
on mfd syscon remove that header and Kconfig dependency.
Tested-by: Alexey Klimov <[email protected]>
Tested-by: Sam Protsenko <[email protected]>
Acked-by: Guenter Roeck <[email protected]>
Reviewed-by: Sam Protsenko <[email protected]>
Signed-off-by: Peter Griffin <[email protected]>
---
drivers/watchdog/Kconfig | 1 -
drivers/watchdog/s3c2410_wdt.c | 8 ++++----
2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 7d22051b15a2..d78fe7137799 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -512,7 +512,6 @@ config S3C2410_WATCHDOG
tristate "S3C6410/S5Pv210/Exynos Watchdog"
depends on ARCH_S3C64XX || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
select WATCHDOG_CORE
- select MFD_SYSCON if ARCH_EXYNOS
help
Watchdog timer block in the Samsung S3C64xx, S5Pv210 and Exynos
SoCs. This will reboot the system when the timer expires with
diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 349d30462c8c..686cf544d0ae 100644
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -24,9 +24,9 @@
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/of.h>
-#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/delay.h>
+#include <linux/soc/samsung/exynos-pmu.h>
#define S3C2410_WTCON 0x00
#define S3C2410_WTDAT 0x04
@@ -699,11 +699,11 @@ static int s3c2410wdt_probe(struct platform_device *pdev)
return ret;
if (wdt->drv_data->quirks & QUIRKS_HAVE_PMUREG) {
- wdt->pmureg = syscon_regmap_lookup_by_phandle(dev->of_node,
- "samsung,syscon-phandle");
+ wdt->pmureg = exynos_get_pmu_regmap_by_phandle(dev->of_node,
+ "samsung,syscon-phandle");
if (IS_ERR(wdt->pmureg))
return dev_err_probe(dev, PTR_ERR(wdt->pmureg),
- "syscon regmap lookup failed.\n");
+ "PMU regmap lookup failed.\n");
}
wdt_irq = platform_get_irq(pdev, 0);
--
2.44.0.rc0.258.g7320e95886-goog
On Tue, 20 Feb 2024 22:06:11 +0000, Peter Griffin wrote:
> This is a v6 of the series to add support for protected PMU registers found
> on gs101 and derivative SoCs. In v2 and later it was re-worked to be based
> on a regmap abstraction that I think leads to a much neater overall
> solution.
>
> The advantage of the regmap abstraction is that most leaf drivers that
> read/write PMU registers need minimal changes.
>
> [...]
Applied, thanks!
[1/2] soc: samsung: exynos-pmu: Add regmap support for SoCs that protect PMU regs
https://git.kernel.org/krzk/linux/c/0b7c6075022ccff529318597dc6b165dd6a25c8f
[2/2] watchdog: s3c2410_wdt: use exynos_get_pmu_regmap_by_phandle() for PMU regs
https://git.kernel.org/krzk/linux/c/746f0770f916e6c48e422d6a34e67eae16707f0e
Best regards,
--
Krzysztof Kozlowski <[email protected]>