soc: renesas: rcar-gen4-sysc: Introduce R-Car Gen4 SYSC driver

According to the official website [1], the R-Car V3U SoC is based
on the R-Car Gen4 architecture. So, introduce R-Car Gen4 SYSC
driver.

[1]
https://www.renesas.com/us/en/products/automotive-products/automotive-system-chips-socs/r-car-v3u-best-class-r-car-v3u-asil-d-system-chip-automated-drivingSigned-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20211201073308.1003945-6-yoshihiro.shimoda.uh@renesas.comSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

drivers/soc/renesas/Kconfig

@@ -297,6 +297,9 @@ config RST_RCAR
 config SYSC_RCAR
 	bool "System Controller support for R-Car" if COMPILE_TEST
 
+config SYSC_RCAR_GEN4
+	bool "System Controller support for R-Car Gen4" if COMPILE_TEST
+
 config SYSC_R8A77995
 	bool "System Controller support for R-Car D3" if COMPILE_TEST
 	select SYSC_RCAR
@@ -351,6 +354,7 @@ config SYSC_R8A77970
 
 config SYSC_R8A779A0
 	bool "System Controller support for R-Car V3U" if COMPILE_TEST
+	select SYSC_RCAR_GEN4
 
 config SYSC_RMOBILE
 	bool "System Controller support for R-Mobile" if COMPILE_TEST

drivers/soc/renesas/Makefile

@@ -32,4 +32,5 @@ endif
 # Family
 obj-$(CONFIG_RST_RCAR)		+= rcar-rst.o
 obj-$(CONFIG_SYSC_RCAR)		+= rcar-sysc.o
+obj-$(CONFIG_SYSC_RCAR_GEN4)	+= rcar-gen4-sysc.o
 obj-$(CONFIG_SYSC_RMOBILE)	+= rmobile-sysc.o

drivers/soc/renesas/rcar-gen4-sysc.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * R-Car Gen4 SYSC Power management support
+ *
+ * Copyright (C) 2021 Renesas Electronics Corp.
+ */
+
+#include <linux/bits.h>
+#include <linux/clk/renesas.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/of_address.h>
+#include <linux/pm_domain.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#include "rcar-gen4-sysc.h"
+
+/* SYSC Common */
+#define SYSCSR		0x000	/* SYSC Status Register */
+#define SYSCPONSR(x)	(0x800 + ((x) * 0x4)) /* Power-ON Status Register 0 */
+#define SYSCPOFFSR(x)	(0x808 + ((x) * 0x4)) /* Power-OFF Status Register */
+#define SYSCISCR(x)	(0x810 + ((x) * 0x4)) /* Interrupt Status/Clear Register */
+#define SYSCIER(x)	(0x820 + ((x) * 0x4)) /* Interrupt Enable Register */
+#define SYSCIMR(x)	(0x830 + ((x) * 0x4)) /* Interrupt Mask Register */
+
+/* Power Domain Registers */
+#define PDRSR(n)	(0x1000 + ((n) * 0x40))
+#define PDRONCR(n)	(0x1004 + ((n) * 0x40))
+#define PDROFFCR(n)	(0x1008 + ((n) * 0x40))
+#define PDRESR(n)	(0x100C + ((n) * 0x40))
+
+/* PWRON/PWROFF */
+#define PWRON_PWROFF		BIT(0)	/* Power-ON/OFF request */
+
+/* PDRESR */
+#define PDRESR_ERR		BIT(0)
+
+/* PDRSR */
+#define PDRSR_OFF		BIT(0)	/* Power-OFF state */
+#define PDRSR_ON		BIT(4)	/* Power-ON state */
+#define PDRSR_OFF_STATE		BIT(8)  /* Processing Power-OFF sequence */
+#define PDRSR_ON_STATE		BIT(12) /* Processing Power-ON sequence */
+
+#define SYSCSR_BUSY		GENMASK(1, 0)	/* All bit sets is not busy */
+
+#define SYSCSR_TIMEOUT		10000
+#define SYSCSR_DELAY_US		10
+
+#define PDRESR_RETRIES		1000
+#define PDRESR_DELAY_US		10
+
+#define SYSCISR_TIMEOUT		10000
+#define SYSCISR_DELAY_US	10
+
+#define RCAR_GEN4_PD_ALWAYS_ON	64
+#define NUM_DOMAINS_EACH_REG	BITS_PER_TYPE(u32)
+
+static void __iomem *rcar_gen4_sysc_base;
+static DEFINE_SPINLOCK(rcar_gen4_sysc_lock); /* SMP CPUs + I/O devices */
+
+static int rcar_gen4_sysc_pwr_on_off(u8 pdr, bool on)
+{
+	unsigned int reg_offs;
+	u32 val;
+	int ret;
+
+	if (on)
+		reg_offs = PDRONCR(pdr);
+	else
+		reg_offs = PDROFFCR(pdr);
+
+	/* Wait until SYSC is ready to accept a power request */
+	ret = readl_poll_timeout_atomic(rcar_gen4_sysc_base + SYSCSR, val,
+					(val & SYSCSR_BUSY) == SYSCSR_BUSY,
+					SYSCSR_DELAY_US, SYSCSR_TIMEOUT);
+	if (ret < 0)
+		return -EAGAIN;
+
+	/* Submit power shutoff or power resume request */
+	iowrite32(PWRON_PWROFF, rcar_gen4_sysc_base + reg_offs);
+
+	return 0;
+}
+
+static int clear_irq_flags(unsigned int reg_idx, unsigned int isr_mask)
+{
+	u32 val;
+	int ret;
+
+	iowrite32(isr_mask, rcar_gen4_sysc_base + SYSCISCR(reg_idx));
+
+	ret = readl_poll_timeout_atomic(rcar_gen4_sysc_base + SYSCISCR(reg_idx),
+					val, !(val & isr_mask),
+					SYSCISR_DELAY_US, SYSCISR_TIMEOUT);
+	if (ret < 0) {
+		pr_err("\n %s : Can not clear IRQ flags in SYSCISCR", __func__);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int rcar_gen4_sysc_power(u8 pdr, bool on)
+{
+	unsigned int isr_mask;
+	unsigned int reg_idx, bit_idx;
+	unsigned int status;
+	unsigned long flags;
+	int ret = 0;
+	u32 val;
+	int k;
+
+	spin_lock_irqsave(&rcar_gen4_sysc_lock, flags);
+
+	reg_idx = pdr / NUM_DOMAINS_EACH_REG;
+	bit_idx = pdr % NUM_DOMAINS_EACH_REG;
+
+	isr_mask = BIT(bit_idx);
+
+	/*
+	 * The interrupt source needs to be enabled, but masked, to prevent the
+	 * CPU from receiving it.
+	 */
+	iowrite32(ioread32(rcar_gen4_sysc_base + SYSCIER(reg_idx)) | isr_mask,
+		  rcar_gen4_sysc_base + SYSCIER(reg_idx));
+	iowrite32(ioread32(rcar_gen4_sysc_base + SYSCIMR(reg_idx)) | isr_mask,
+		  rcar_gen4_sysc_base + SYSCIMR(reg_idx));
+
+	ret = clear_irq_flags(reg_idx, isr_mask);
+	if (ret)
+		goto out;
+
+	/* Submit power shutoff or resume request until it was accepted */
+	for (k = 0; k < PDRESR_RETRIES; k++) {
+		ret = rcar_gen4_sysc_pwr_on_off(pdr, on);
+		if (ret)
+			goto out;
+
+		status = ioread32(rcar_gen4_sysc_base + PDRESR(pdr));
+		if (!(status & PDRESR_ERR))
+			break;
+
+		udelay(PDRESR_DELAY_US);
+	}
+
+	if (k == PDRESR_RETRIES) {
+		ret = -EIO;
+		goto out;
+	}
+
+	/* Wait until the power shutoff or resume request has completed * */
+	ret = readl_poll_timeout_atomic(rcar_gen4_sysc_base + SYSCISCR(reg_idx),
+					val, (val & isr_mask),
+					SYSCISR_DELAY_US, SYSCISR_TIMEOUT);
+	if (ret < 0) {
+		ret = -EIO;
+		goto out;
+	}
+
+	/* Clear interrupt flags */
+	ret = clear_irq_flags(reg_idx, isr_mask);
+	if (ret)
+		goto out;
+
+ out:
+	spin_unlock_irqrestore(&rcar_gen4_sysc_lock, flags);
+
+	pr_debug("sysc power %s domain %d: %08x -> %d\n", on ? "on" : "off",
+		 pdr, ioread32(rcar_gen4_sysc_base + SYSCISCR(reg_idx)), ret);
+	return ret;
+}
+
+static bool rcar_gen4_sysc_power_is_off(u8 pdr)
+{
+	unsigned int st;
+
+	st = ioread32(rcar_gen4_sysc_base + PDRSR(pdr));
+
+	if (st & PDRSR_OFF)
+		return true;
+
+	return false;
+}
+
+struct rcar_gen4_sysc_pd {
+	struct generic_pm_domain genpd;
+	u8 pdr;
+	unsigned int flags;
+	char name[];
+};
+
+static inline struct rcar_gen4_sysc_pd *to_rcar_gen4_pd(struct generic_pm_domain *d)
+{
+	return container_of(d, struct rcar_gen4_sysc_pd, genpd);
+}
+
+static int rcar_gen4_sysc_pd_power_off(struct generic_pm_domain *genpd)
+{
+	struct rcar_gen4_sysc_pd *pd = to_rcar_gen4_pd(genpd);
+
+	pr_debug("%s: %s\n", __func__, genpd->name);
+	return rcar_gen4_sysc_power(pd->pdr, false);
+}
+
+static int rcar_gen4_sysc_pd_power_on(struct generic_pm_domain *genpd)
+{
+	struct rcar_gen4_sysc_pd *pd = to_rcar_gen4_pd(genpd);
+
+	pr_debug("%s: %s\n", __func__, genpd->name);
+	return rcar_gen4_sysc_power(pd->pdr, true);
+}
+
+static int __init rcar_gen4_sysc_pd_setup(struct rcar_gen4_sysc_pd *pd)
+{
+	struct generic_pm_domain *genpd = &pd->genpd;
+	const char *name = pd->genpd.name;
+	int error;
+
+	if (pd->flags & PD_CPU) {
+		/*
+		 * This domain contains a CPU core and therefore it should
+		 * only be turned off if the CPU is not in use.
+		 */
+		pr_debug("PM domain %s contains %s\n", name, "CPU");
+		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
+	} else if (pd->flags & PD_SCU) {
+		/*
+		 * This domain contains an SCU and cache-controller, and
+		 * therefore it should only be turned off if the CPU cores are
+		 * not in use.
+		 */
+		pr_debug("PM domain %s contains %s\n", name, "SCU");
+		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
+	} else if (pd->flags & PD_NO_CR) {
+		/*
+		 * This domain cannot be turned off.
+		 */
+		genpd->flags |= GENPD_FLAG_ALWAYS_ON;
+	}
+
+	if (!(pd->flags & (PD_CPU | PD_SCU))) {
+		/* Enable Clock Domain for I/O devices */
+		genpd->flags |= GENPD_FLAG_PM_CLK | GENPD_FLAG_ACTIVE_WAKEUP;
+		genpd->attach_dev = cpg_mssr_attach_dev;
+		genpd->detach_dev = cpg_mssr_detach_dev;
+	}
+
+	genpd->power_off = rcar_gen4_sysc_pd_power_off;
+	genpd->power_on = rcar_gen4_sysc_pd_power_on;
+
+	if (pd->flags & (PD_CPU | PD_NO_CR)) {
+		/* Skip CPUs (handled by SMP code) and areas without control */
+		pr_debug("%s: Not touching %s\n", __func__, genpd->name);
+		goto finalize;
+	}
+
+	if (!rcar_gen4_sysc_power_is_off(pd->pdr)) {
+		pr_debug("%s: %s is already powered\n", __func__, genpd->name);
+		goto finalize;
+	}
+
+	rcar_gen4_sysc_power(pd->pdr, true);
+
+finalize:
+	error = pm_genpd_init(genpd, &simple_qos_governor, false);
+	if (error)
+		pr_err("Failed to init PM domain %s: %d\n", name, error);
+
+	return error;
+}
+
+static const struct of_device_id rcar_gen4_sysc_matches[] __initconst = {
+#ifdef CONFIG_SYSC_R8A779A0
+	{ .compatible = "renesas,r8a779a0-sysc", .data = &r8a779a0_sysc_info },
+#endif
+	{ /* sentinel */ }
+};
+
+struct rcar_gen4_pm_domains {
+	struct genpd_onecell_data onecell_data;
+	struct generic_pm_domain *domains[RCAR_GEN4_PD_ALWAYS_ON + 1];
+};
+
+static struct genpd_onecell_data *rcar_gen4_sysc_onecell_data;
+
+static int __init rcar_gen4_sysc_pd_init(void)
+{
+	const struct rcar_gen4_sysc_info *info;
+	const struct of_device_id *match;
+	struct rcar_gen4_pm_domains *domains;
+	struct device_node *np;
+	void __iomem *base;
+	unsigned int i;
+	int error;
+
+	np = of_find_matching_node_and_match(NULL, rcar_gen4_sysc_matches, &match);
+	if (!np)
+		return -ENODEV;
+
+	info = match->data;
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		pr_warn("%pOF: Cannot map regs\n", np);
+		error = -ENOMEM;
+		goto out_put;
+	}
+
+	rcar_gen4_sysc_base = base;
+
+	domains = kzalloc(sizeof(*domains), GFP_KERNEL);
+	if (!domains) {
+		error = -ENOMEM;
+		goto out_put;
+	}
+
+	domains->onecell_data.domains = domains->domains;
+	domains->onecell_data.num_domains = ARRAY_SIZE(domains->domains);
+	rcar_gen4_sysc_onecell_data = &domains->onecell_data;
+
+	for (i = 0; i < info->num_areas; i++) {
+		const struct rcar_gen4_sysc_area *area = &info->areas[i];
+		struct rcar_gen4_sysc_pd *pd;
+		size_t n;
+
+		if (!area->name) {
+			/* Skip NULLified area */
+			continue;
+		}
+
+		n = strlen(area->name) + 1;
+		pd = kzalloc(sizeof(*pd) + n, GFP_KERNEL);
+		if (!pd) {
+			error = -ENOMEM;
+			goto out_put;
+		}
+
+		memcpy(pd->name, area->name, n);
+		pd->genpd.name = pd->name;
+		pd->pdr = area->pdr;
+		pd->flags = area->flags;
+
+		error = rcar_gen4_sysc_pd_setup(pd);
+		if (error)
+			goto out_put;
+
+		domains->domains[area->pdr] = &pd->genpd;
+
+		if (area->parent < 0)
+			continue;
+
+		error = pm_genpd_add_subdomain(domains->domains[area->parent],
+					       &pd->genpd);
+		if (error) {
+			pr_warn("Failed to add PM subdomain %s to parent %u\n",
+				area->name, area->parent);
+			goto out_put;
+		}
+	}
+
+	error = of_genpd_add_provider_onecell(np, &domains->onecell_data);
+
+out_put:
+	of_node_put(np);
+	return error;
+}
+early_initcall(rcar_gen4_sysc_pd_init);

drivers/soc/renesas/rcar-gen4-sysc.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * R-Car Gen4 System Controller
+ *
+ * Copyright (C) 2021 Renesas Electronics Corp.
+ */
+#ifndef __SOC_RENESAS_RCAR_GEN4_SYSC_H__
+#define __SOC_RENESAS_RCAR_GEN4_SYSC_H__
+
+#include <linux/types.h>
+
+/*
+ * Power Domain flags
+ */
+#define PD_CPU		BIT(0)	/* Area contains main CPU core */
+#define PD_SCU		BIT(1)	/* Area contains SCU and L2 cache */
+#define PD_NO_CR	BIT(2)	/* Area lacks PWR{ON,OFF}CR registers */
+
+#define PD_CPU_NOCR	(PD_CPU | PD_NO_CR) /* CPU area lacks CR */
+#define PD_ALWAYS_ON	PD_NO_CR	  /* Always-on area */
+
+/*
+ * Description of a Power Area
+ */
+struct rcar_gen4_sysc_area {
+	const char *name;
+	u8 pdr;			/* PDRn */
+	int parent;		/* -1 if none */
+	unsigned int flags;	/* See PD_* */
+};
+
+/*
+ * SoC-specific Power Area Description
+ */
+struct rcar_gen4_sysc_info {
+	const struct rcar_gen4_sysc_area *areas;
+	unsigned int num_areas;
+};
+
+extern const struct rcar_gen4_sysc_info r8a779a0_sysc_info;
+
+#endif /* __SOC_RENESAS_RCAR_GEN4_SYSC_H__ */