soc: starfive: Add StarFive JH71XX pmu driver

Add pmu driver for the StarFive JH71XX SoC.

As the power domains provider, the Power Management Unit (PMU) is
designed for including multiple PM domains that can be used for power
gating of selected IP blocks for power saving by reduced leakage
current. It accepts software encourage command to switch the power mode
of SoC.

Signed-off-by: Walker Chen <walker.chen@starfivetech.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>

6 files changed, 413 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index f61eb221415b..305246e5d574 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -19905,6 +19905,19 @@ F:	Documentation/devicetree/bindings/reset/starfive,jh7100-reset.yaml
 F:	drivers/reset/reset-starfive-jh7100.c
 F:	include/dt-bindings/reset/starfive-jh7100.h
 
+STARFIVE SOC DRIVERS
+M:	Conor Dooley <conor@kernel.org>
+S:	Maintained
+T:	git https://git.kernel.org/pub/scm/linux/kernel/git/conor/linux.git/
+F:	drivers/soc/starfive/
+
+STARFIVE JH71XX PMU CONTROLLER DRIVER
+M:	Walker Chen <walker.chen@starfivetech.com>
+S:	Supported
+F:	Documentation/devicetree/bindings/power/starfive*
+F:	drivers/soc/starfive/jh71xx_pmu.c
+F:	include/dt-bindings/power/starfive,jh7110-pmu.h
+
 STATIC BRANCH/CALL
 M:	Peter Zijlstra <peterz@infradead.org>
 M:	Josh Poimboeuf <jpoimboe@kernel.org>
diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
index 5dbb09f843f7..81ae4f77974b 100644
--- a/drivers/soc/Kconfig
+++ b/drivers/soc/Kconfig
@@ -22,6 +22,7 @@ source "drivers/soc/renesas/Kconfig"
 source "drivers/soc/rockchip/Kconfig"
 source "drivers/soc/samsung/Kconfig"
 source "drivers/soc/sifive/Kconfig"
+source "drivers/soc/starfive/Kconfig"
 source "drivers/soc/sunxi/Kconfig"
 source "drivers/soc/tegra/Kconfig"
 source "drivers/soc/ti/Kconfig"
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index fff513bd522d..bc7491d9e1ed 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -28,6 +28,7 @@ obj-y				+= renesas/
 obj-y				+= rockchip/
 obj-$(CONFIG_SOC_SAMSUNG)	+= samsung/
 obj-$(CONFIG_SOC_SIFIVE)	+= sifive/
+obj-$(CONFIG_SOC_STARFIVE)	+= starfive/
 obj-y				+= sunxi/
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra/
 obj-y				+= ti/
diff --git a/drivers/soc/starfive/Kconfig b/drivers/soc/starfive/Kconfig
new file mode 100644
index 000000000000..bdb96dc4c989
--- /dev/null
+++ b/drivers/soc/starfive/Kconfig
@@ -0,0 +1,12 @@
+# SPDX-License-Identifier: GPL-2.0
+
+config JH71XX_PMU
+	bool "Support PMU for StarFive JH71XX Soc"
+	depends on PM
+	depends on SOC_STARFIVE || COMPILE_TEST
+	default SOC_STARFIVE
+	select PM_GENERIC_DOMAINS
+	help
+	  Say 'y' here to enable support power domain support.
+	  In order to meet low power requirements, a Power Management Unit (PMU)
+	  is designed for controlling power resources in StarFive JH71XX SoCs.
diff --git a/drivers/soc/starfive/Makefile b/drivers/soc/starfive/Makefile
new file mode 100644
index 000000000000..13b589d6b5f3
--- /dev/null
+++ b/drivers/soc/starfive/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_JH71XX_PMU)	+= jh71xx_pmu.o
diff --git a/drivers/soc/starfive/jh71xx_pmu.c b/drivers/soc/starfive/jh71xx_pmu.c
new file mode 100644
index 000000000000..7d5f50d71c0d
--- /dev/null
+++ b/drivers/soc/starfive/jh71xx_pmu.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * StarFive JH71XX PMU (Power Management Unit) Controller Driver
+ *
+ * Copyright (C) 2022 StarFive Technology Co., Ltd.
+ */
+
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <dt-bindings/power/starfive,jh7110-pmu.h>
+
+/* register offset */
+#define JH71XX_PMU_SW_TURN_ON_POWER	0x0C
+#define JH71XX_PMU_SW_TURN_OFF_POWER	0x10
+#define JH71XX_PMU_SW_ENCOURAGE		0x44
+#define JH71XX_PMU_TIMER_INT_MASK	0x48
+#define JH71XX_PMU_CURR_POWER_MODE	0x80
+#define JH71XX_PMU_EVENT_STATUS		0x88
+#define JH71XX_PMU_INT_STATUS		0x8C
+
+/* sw encourage cfg */
+#define JH71XX_PMU_SW_ENCOURAGE_EN_LO	0x05
+#define JH71XX_PMU_SW_ENCOURAGE_EN_HI	0x50
+#define JH71XX_PMU_SW_ENCOURAGE_DIS_LO	0x0A
+#define JH71XX_PMU_SW_ENCOURAGE_DIS_HI	0xA0
+#define JH71XX_PMU_SW_ENCOURAGE_ON	0xFF
+
+/* pmu int status */
+#define JH71XX_PMU_INT_SEQ_DONE		BIT(0)
+#define JH71XX_PMU_INT_HW_REQ		BIT(1)
+#define JH71XX_PMU_INT_SW_FAIL		GENMASK(3, 2)
+#define JH71XX_PMU_INT_HW_FAIL		GENMASK(5, 4)
+#define JH71XX_PMU_INT_PCH_FAIL		GENMASK(8, 6)
+#define JH71XX_PMU_INT_ALL_MASK		GENMASK(8, 0)
+
+/*
+ * The time required for switching power status is based on the time
+ * to turn on the largest domain's power, which is at microsecond level
+ */
+#define JH71XX_PMU_TIMEOUT_US		100
+
+struct jh71xx_domain_info {
+	const char * const name;
+	unsigned int flags;
+	u8 bit;
+};
+
+struct jh71xx_pmu_match_data {
+	const struct jh71xx_domain_info *domain_info;
+	int num_domains;
+};
+
+struct jh71xx_pmu {
+	struct device *dev;
+	const struct jh71xx_pmu_match_data *match_data;
+	void __iomem *base;
+	struct generic_pm_domain **genpd;
+	struct genpd_onecell_data genpd_data;
+	int irq;
+	spinlock_t lock;	/* protects pmu reg */
+};
+
+struct jh71xx_pmu_dev {
+	const struct jh71xx_domain_info *domain_info;
+	struct jh71xx_pmu *pmu;
+	struct generic_pm_domain genpd;
+};
+
+static int jh71xx_pmu_get_state(struct jh71xx_pmu_dev *pmd, u32 mask, bool *is_on)
+{
+	struct jh71xx_pmu *pmu = pmd->pmu;
+
+	if (!mask)
+		return -EINVAL;
+
+	*is_on = readl(pmu->base + JH71XX_PMU_CURR_POWER_MODE) & mask;
+
+	return 0;
+}
+
+static int jh71xx_pmu_set_state(struct jh71xx_pmu_dev *pmd, u32 mask, bool on)
+{
+	struct jh71xx_pmu *pmu = pmd->pmu;
+	unsigned long flags;
+	u32 val;
+	u32 mode;
+	u32 encourage_lo;
+	u32 encourage_hi;
+	bool is_on;
+	int ret;
+
+	ret = jh71xx_pmu_get_state(pmd, mask, &is_on);
+	if (ret) {
+		dev_dbg(pmu->dev, "unable to get current state for %s\n",
+			pmd->genpd.name);
+		return ret;
+	}
+
+	if (is_on == on) {
+		dev_dbg(pmu->dev, "pm domain [%s] is already %sable status.\n",
+			pmd->genpd.name, on ? "en" : "dis");
+		return 0;
+	}
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	/*
+	 * The PMU accepts software encourage to switch power mode in the following 2 steps:
+	 *
+	 * 1.Configure the register SW_TURN_ON_POWER (offset 0x0c) by writing 1 to
+	 *   the bit corresponding to the power domain that will be turned on
+	 *   and writing 0 to the others.
+	 *   Likewise, configure the register SW_TURN_OFF_POWER (offset 0x10) by
+	 *   writing 1 to the bit corresponding to the power domain that will be
+	 *   turned off and writing 0 to the others.
+	 */
+	if (on) {
+		mode = JH71XX_PMU_SW_TURN_ON_POWER;
+		encourage_lo = JH71XX_PMU_SW_ENCOURAGE_EN_LO;
+		encourage_hi = JH71XX_PMU_SW_ENCOURAGE_EN_HI;
+	} else {
+		mode = JH71XX_PMU_SW_TURN_OFF_POWER;
+		encourage_lo = JH71XX_PMU_SW_ENCOURAGE_DIS_LO;
+		encourage_hi = JH71XX_PMU_SW_ENCOURAGE_DIS_HI;
+	}
+
+	writel(mask, pmu->base + mode);
+
+	/*
+	 * 2.Write SW encourage command sequence to the Software Encourage Reg (offset 0x44)
+	 *   First write SW_MODE_ENCOURAGE_ON to JH71XX_PMU_SW_ENCOURAGE. This will reset
+	 *   the state machine which parses the command sequence. This register must be
+	 *   written every time software wants to power on/off a domain.
+	 *   Then write the lower bits of the command sequence, followed by the upper
+	 *   bits. The sequence differs between powering on & off a domain.
+	 */
+	writel(JH71XX_PMU_SW_ENCOURAGE_ON, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
+	writel(encourage_lo, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
+	writel(encourage_hi, pmu->base + JH71XX_PMU_SW_ENCOURAGE);
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	/* Wait for the power domain bit to be enabled / disabled */
+	if (on) {
+		ret = readl_poll_timeout_atomic(pmu->base + JH71XX_PMU_CURR_POWER_MODE,
+						val, val & mask,
+						1, JH71XX_PMU_TIMEOUT_US);
+	} else {
+		ret = readl_poll_timeout_atomic(pmu->base + JH71XX_PMU_CURR_POWER_MODE,
+						val, !(val & mask),
+						1, JH71XX_PMU_TIMEOUT_US);
+	}
+
+	if (ret) {
+		dev_err(pmu->dev, "%s: failed to power %s\n",
+			pmd->genpd.name, on ? "on" : "off");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+
+static int jh71xx_pmu_on(struct generic_pm_domain *genpd)
+{
+	struct jh71xx_pmu_dev *pmd = container_of(genpd,
+						  struct jh71xx_pmu_dev, genpd);
+	u32 pwr_mask = BIT(pmd->domain_info->bit);
+
+	return jh71xx_pmu_set_state(pmd, pwr_mask, true);
+}
+
+static int jh71xx_pmu_off(struct generic_pm_domain *genpd)
+{
+	struct jh71xx_pmu_dev *pmd = container_of(genpd,
+						  struct jh71xx_pmu_dev, genpd);
+	u32 pwr_mask = BIT(pmd->domain_info->bit);
+
+	return jh71xx_pmu_set_state(pmd, pwr_mask, false);
+}
+
+static void jh71xx_pmu_int_enable(struct jh71xx_pmu *pmu, u32 mask, bool enable)
+{
+	u32 val;
+	unsigned long flags;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+	val = readl(pmu->base + JH71XX_PMU_TIMER_INT_MASK);
+
+	if (enable)
+		val &= ~mask;
+	else
+		val |= mask;
+
+	writel(val, pmu->base + JH71XX_PMU_TIMER_INT_MASK);
+	spin_unlock_irqrestore(&pmu->lock, flags);
+}
+
+static irqreturn_t jh71xx_pmu_interrupt(int irq, void *data)
+{
+	struct jh71xx_pmu *pmu = data;
+	u32 val;
+
+	val = readl(pmu->base + JH71XX_PMU_INT_STATUS);
+
+	if (val & JH71XX_PMU_INT_SEQ_DONE)
+		dev_dbg(pmu->dev, "sequence done.\n");
+	if (val & JH71XX_PMU_INT_HW_REQ)
+		dev_dbg(pmu->dev, "hardware encourage requestion.\n");
+	if (val & JH71XX_PMU_INT_SW_FAIL)
+		dev_err(pmu->dev, "software encourage fail.\n");
+	if (val & JH71XX_PMU_INT_HW_FAIL)
+		dev_err(pmu->dev, "hardware encourage fail.\n");
+	if (val & JH71XX_PMU_INT_PCH_FAIL)
+		dev_err(pmu->dev, "p-channel fail event.\n");
+
+	/* clear interrupts */
+	writel(val, pmu->base + JH71XX_PMU_INT_STATUS);
+	writel(val, pmu->base + JH71XX_PMU_EVENT_STATUS);
+
+	return IRQ_HANDLED;
+}
+
+static int jh71xx_pmu_init_domain(struct jh71xx_pmu *pmu, int index)
+{
+	struct jh71xx_pmu_dev *pmd;
+	u32 pwr_mask;
+	int ret;
+	bool is_on = false;
+
+	pmd = devm_kzalloc(pmu->dev, sizeof(*pmd), GFP_KERNEL);
+	if (!pmd)
+		return -ENOMEM;
+
+	pmd->domain_info = &pmu->match_data->domain_info[index];
+	pmd->pmu = pmu;
+	pwr_mask = BIT(pmd->domain_info->bit);
+
+	pmd->genpd.name = pmd->domain_info->name;
+	pmd->genpd.flags = pmd->domain_info->flags;
+
+	ret = jh71xx_pmu_get_state(pmd, pwr_mask, &is_on);
+	if (ret)
+		dev_warn(pmu->dev, "unable to get current state for %s\n",
+			 pmd->genpd.name);
+
+	pmd->genpd.power_on = jh71xx_pmu_on;
+	pmd->genpd.power_off = jh71xx_pmu_off;
+	pm_genpd_init(&pmd->genpd, NULL, !is_on);
+
+	pmu->genpd_data.domains[index] = &pmd->genpd;
+
+	return 0;
+}
+
+static int jh71xx_pmu_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	const struct jh71xx_pmu_match_data *match_data;
+	struct jh71xx_pmu *pmu;
+	unsigned int i;
+	int ret;
+
+	pmu = devm_kzalloc(dev, sizeof(*pmu), GFP_KERNEL);
+	if (!pmu)
+		return -ENOMEM;
+
+	pmu->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(pmu->base))
+		return PTR_ERR(pmu->base);
+
+	pmu->irq = platform_get_irq(pdev, 0);
+	if (pmu->irq < 0)
+		return pmu->irq;
+
+	ret = devm_request_irq(dev, pmu->irq, jh71xx_pmu_interrupt,
+			       0, pdev->name, pmu);
+	if (ret)
+		dev_err(dev, "failed to request irq\n");
+
+	match_data = of_device_get_match_data(dev);
+	if (!match_data)
+		return -EINVAL;
+
+	pmu->genpd = devm_kcalloc(dev, match_data->num_domains,
+				  sizeof(struct generic_pm_domain *),
+				  GFP_KERNEL);
+	if (!pmu->genpd)
+		return -ENOMEM;
+
+	pmu->dev = dev;
+	pmu->match_data = match_data;
+	pmu->genpd_data.domains = pmu->genpd;
+	pmu->genpd_data.num_domains = match_data->num_domains;
+
+	for (i = 0; i < match_data->num_domains; i++) {
+		ret = jh71xx_pmu_init_domain(pmu, i);
+		if (ret) {
+			dev_err(dev, "failed to initialize power domain\n");
+			return ret;
+		}
+	}
+
+	spin_lock_init(&pmu->lock);
+	jh71xx_pmu_int_enable(pmu, JH71XX_PMU_INT_ALL_MASK & ~JH71XX_PMU_INT_PCH_FAIL, true);
+
+	ret = of_genpd_add_provider_onecell(np, &pmu->genpd_data);
+	if (ret) {
+		dev_err(dev, "failed to register genpd driver: %d\n", ret);
+		return ret;
+	}
+
+	dev_dbg(dev, "registered %u power domains\n", i);
+
+	return 0;
+}
+
+static const struct jh71xx_domain_info jh7110_power_domains[] = {
+	[JH7110_PD_SYSTOP] = {
+		.name = "SYSTOP",
+		.bit = 0,
+		.flags = GENPD_FLAG_ALWAYS_ON,
+	},
+	[JH7110_PD_CPU] = {
+		.name = "CPU",
+		.bit = 1,
+		.flags = GENPD_FLAG_ALWAYS_ON,
+	},
+	[JH7110_PD_GPUA] = {
+		.name = "GPUA",
+		.bit = 2,
+	},
+	[JH7110_PD_VDEC] = {
+		.name = "VDEC",
+		.bit = 3,
+	},
+	[JH7110_PD_VOUT] = {
+		.name = "VOUT",
+		.bit = 4,
+	},
+	[JH7110_PD_ISP] = {
+		.name = "ISP",
+		.bit = 5,
+	},
+	[JH7110_PD_VENC] = {
+		.name = "VENC",
+		.bit = 6,
+	},
+};
+
+static const struct jh71xx_pmu_match_data jh7110_pmu = {
+	.num_domains = ARRAY_SIZE(jh7110_power_domains),
+	.domain_info = jh7110_power_domains,
+};
+
+static const struct of_device_id jh71xx_pmu_of_match[] = {
+	{
+		.compatible = "starfive,jh7110-pmu",
+		.data = (void *)&jh7110_pmu,
+	}, {
+		/* sentinel */
+	}
+};
+
+static struct platform_driver jh71xx_pmu_driver = {
+	.probe = jh71xx_pmu_probe,
+	.driver = {
+		.name = "jh71xx-pmu",
+		.of_match_table = jh71xx_pmu_of_match,
+		.suppress_bind_attrs = true,
+	},
+};
+builtin_platform_driver(jh71xx_pmu_driver);
+
+MODULE_AUTHOR("Walker Chen <walker.chen@starfivetech.com>");
+MODULE_DESCRIPTION("StarFive JH71XX PMU Driver");
+MODULE_LICENSE("GPL");