[PATCH v8 05/10] pmdomain: samsung: convert to using regmap

André Draszik
2026-03-18T15:28:03Z

On platforms such as Google gs101, direct mmio register access to the
PMU registers doesn't necessarily work and access must happen via a
regmap created by the PMU driver instead.

In preparation for supporting such SoCs convert the existing mmio
accesses to using a regmap wrapper.

With this change in place, a follow-up patch can update the driver to
optionally acquire the PMU-created regmap without having to change the
rest of the code.

Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: André Draszik <andre.draszik@linaro.org>
---
There is one checkpatch warning, relating to the non-const
regmap_config. It can not easily be made const at this stage, but a
follow-up patch allows us to make it const and the warning will go away
anyway.

v8:
- add missing \n in some of the new log messages

v4:
- rework the loop in exynos_pd_power() slightly, to not return 0 early
to allow more code to be run after pd on/off register write without
changing the loop again, required for gs101.
- add error message in case first regmap write in exynos_pd_power() fails
---
drivers/pmdomain/samsung/exynos-pm-domains.c | 83 +++++++++++++++++++++-------
1 file changed, 62 insertions(+), 21 deletions(-)

diff --git a/drivers/pmdomain/samsung/exynos-pm-domains.c b/drivers/pmdomain/samsung/exynos-pm-domains.c
index 5c3aa8983087..68b1e7ba8729 100644
--- a/drivers/pmdomain/samsung/exynos-pm-domains.c
+++ b/drivers/pmdomain/samsung/exynos-pm-domains.c
@@ -9,15 +9,14 @@
// conjunction with runtime-pm. Support for both device-tree and non-device-tree
// based power domain support is included.

-#include <linux/io.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/pm_domain.h>
#include <linux/delay.h>
#include <linux/of.h>
-#include <linux/of_address.h>
#include <linux/pm_runtime.h>
+#include <linux/regmap.h>

struct exynos_pm_domain_config {
/* Value for LOCAL_PWR_CFG and STATUS fields for each domain */
@@ -28,7 +27,7 @@ struct exynos_pm_domain_config {
* Exynos specific wrapper around the generic power domain
*/
struct exynos_pm_domain {
- void __iomem *base;
+ struct regmap *regmap;
struct generic_pm_domain pd;
u32 local_pwr_cfg;
};
@@ -36,31 +35,42 @@ struct exynos_pm_domain {
static int exynos_pd_power(struct generic_pm_domain *domain, bool power_on)
{
struct exynos_pm_domain *pd;
- void __iomem *base;
u32 timeout, pwr;
- char *op;
+ int err;

pd = container_of(domain, struct exynos_pm_domain, pd);
- base = pd->base;

pwr = power_on ? pd->local_pwr_cfg : 0;
- writel_relaxed(pwr, base);
+ err = regmap_write(pd->regmap, 0, pwr);
+ if (err) {
+ pr_err("Regmap write for power domain %s %sable failed: %d\n",
+ domain->name, power_on ? "en" : "dis", err);
+ return err;
+ }

/* Wait max 1ms */
timeout = 10;
-
- while ((readl_relaxed(base + 0x4) & pd->local_pwr_cfg) != pwr) {
- if (!timeout) {
- op = (power_on) ? "enable" : "disable";
- pr_err("Power domain %s %s failed\n", domain->name, op);
- return -ETIMEDOUT;
+ while (timeout-- > 0) {
+ unsigned int val;
+
+ err = regmap_read(pd->regmap, 0x4, &val);
+ if (err || ((val & pd->local_pwr_cfg) != pwr)) {
+ cpu_relax();
+ usleep_range(80, 100);
+ continue;
}
- timeout--;
- cpu_relax();
- usleep_range(80, 100);
+
+ break;
}

- return 0;
+ if (!timeout && !err)
+ /* Only return timeout if no other error also occurred. */
+ err = -ETIMEDOUT;
+ if (err)
+ pr_err("Power domain %s %sable failed: %d\n", domain->name,
+ power_on ? "en" : "dis", err);
+
+ return err;
}

static int exynos_pd_power_on(struct generic_pm_domain *domain)
@@ -109,8 +119,18 @@ static int exynos_pd_probe(struct platform_device *pdev)
struct device_node *np = dev->of_node;
struct of_phandle_args child, parent;
struct exynos_pm_domain *pd;
+ struct resource *res;
+ void __iomem *base;
+ unsigned int val;
int on, ret;

+ struct regmap_config reg_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+ .use_relaxed_mmio = true,
+ };
+
pm_domain_cfg = of_device_get_match_data(dev);
pd = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
if (!pd)
@@ -120,9 +140,26 @@ static int exynos_pd_probe(struct platform_device *pdev)
if (!pd->pd.name)
return -ENOMEM;

- pd->base = of_iomap(np, 0);
- if (!pd->base)
- return -ENODEV;
+ /*
+ * The resource typically points into the address space of the PMU.
+ * Therefore, avoid using devm_platform_get_and_ioremap_resource() and
+ * instead use platform_get_resource() and devm_ioremap() to avoid
+ * conflicts due to address space overlap.
+ */
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return dev_err_probe(dev, -ENXIO, "missing IO resources\n");
+
+ base = devm_ioremap(dev, res->start, resource_size(res));
+ if (!base)
+ return dev_err_probe(dev, -ENOMEM,
+ "failed to ioremap PMU regs\n");
+
+ reg_config.max_register = resource_size(res) - reg_config.reg_stride;
+ pd->regmap = devm_regmap_init_mmio(dev, base, &reg_config);
+ if (IS_ERR(pd->regmap))
+ return dev_err_probe(dev, PTR_ERR(base),
+ "failed to init regmap\n");

pd->pd.power_off = exynos_pd_power_off;
pd->pd.power_on = exynos_pd_power_on;
@@ -137,7 +174,11 @@ static int exynos_pd_probe(struct platform_device *pdev)
of_device_is_compatible(np, "samsung,exynos4210-pd"))
exynos_pd_power_off(&pd->pd);

- on = readl_relaxed(pd->base + 0x4) & pd->local_pwr_cfg;
+ ret = regmap_read(pd->regmap, 0x4, &val);
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to read status\n");
+
+ on = val & pd->local_pwr_cfg;

pm_genpd_init(&pd->pd, NULL, !on);
ret = of_genpd_add_provider_simple(np, &pd->pd);

--
2.53.0.851.ga537e3e6e9-goog