[PATCH 04/10] pmdomain: samsung: convert to using regmap

["André Draszik" <andre.draszik@linaro.org>]

On platforms such as Google gs101, direct mmio register access to the
PMU registers doesn't necessarily work and access must happen via a
(syscon) 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.

Signed-off-by: André Draszik <andre.draszik@linaro.org>

---
There is one checkpatch warning, relating to the non-const
regmap_config. It can a) not be made const without resorting to having
two copies and copying, and b) will go away in a follow-up patch
anyway.
---
 drivers/pmdomain/samsung/exynos-pm-domains.c | 78 ++++++++++++++++++++--------
 1 file changed, 57 insertions(+), 21 deletions(-)

diff --git a/drivers/pmdomain/samsung/exynos-pm-domains.c b/drivers/pmdomain/samsung/exynos-pm-domains.c
index f53e1bd2479807988f969774b4b7b4c5739c1aba..383126245811cb8e4dbae3b99ced3f06d3093f35 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 +35,37 @@ 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)
+		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);
+
+		return 0;
 	}
 
-	return 0;
+	if (!err)
+		err = -ETIMEDOUT;
+	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 +114,18 @@ 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)
@@ -120,15 +135,36 @@ 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");
+
+	base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!base)
+		return dev_err_probe(dev, -ENOMEM,
+				     "failed to ioremap PMU registers");
+
+	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");
 
 	pd->pd.power_off = exynos_pd_power_off;
 	pd->pd.power_on = exynos_pd_power_on;
 	pd->local_pwr_cfg = pm_domain_cfg->local_pwr_cfg;
 
-	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");
+
+	on = val & pd->local_pwr_cfg;
 
 	pm_genpd_init(&pd->pd, NULL, !on);
 	ret = of_genpd_add_provider_simple(np, &pd->pd);

-- 
2.51.0.618.g983fd99d29-goog