[PATCH/RFC 02/15] ARM: shmobile: R-Car: Add DT support for PM domains

[Geert Uytterhoeven]

Populate the PM domains from DT.

Special cases, like PM domains containing CPU cores or SCUs, are
handled by scanning the DT topology.

The SYSCIER register value is derived from the PM domains found in DT,
which will allow to get rid of the hardcoded values in pm-rcar-gen2.c.
However, this means we have to scan for PM domains even if CONFIG_PM=n.

Known issues:
  - Although this supports R-Car H1 (r8a7779), the DT PM domain code
    conflicts with the current setup code in pm-r8a7779, which is used
    regardless of DT,
  - This needs better integration with the PM code in pm-rcar-gen2, and
    the SMP code in smp-r8a7790.

Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
 arch/arm/mach-shmobile/pm-rcar.c | 299 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 299 insertions(+)

diff --git a/arch/arm/mach-shmobile/pm-rcar.c b/arch/arm/mach-shmobile/pm-rcar.c
index 4092ad16e0a42a26..13e5f1ee8d89d296 100644
--- a/arch/arm/mach-shmobile/pm-rcar.c
+++ b/arch/arm/mach-shmobile/pm-rcar.c
@@ -11,6 +11,9 @@
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/mm.h>
+#include <linux/of_address.h>
+#include <linux/pm_domain.h>
+#include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <asm/io.h>
 #include "pm-rcar.h"
@@ -51,11 +54,29 @@
 static void __iomem *rcar_sysc_base;
 static DEFINE_SPINLOCK(rcar_sysc_lock); /* SMP CPUs + I/O devices */
 
+static unsigned int rcar_gen;
+
 static int rcar_sysc_pwr_on_off(const struct rcar_sysc_ch *sysc_ch, bool on)
 {
 	unsigned int sr_bit, reg_offs;
 	int k;
 
+	/*
+	 * Only R-Car H1 can control power to CPUs
+	 * Use WFI to power off, CPG/APMU to resume ARM cores on later R-Car
+	 * Generations
+	 */
+	switch (rcar_gen) {
+	case 2:
+		/* FIXME Check rcar_pm_domain.cpu instead? */
+		switch (sysc_ch->chan_offs) {
+		case SYSC_PWR_CA15_CPU:
+		case SYSC_PWR_CA7_CPU:
+			pr_err("%s: Cannot control power to CPU\n", __func__);
+			return -EINVAL;
+		}
+	}
+
 	if (on) {
 		sr_bit = SYSCSR_PONENB;
 		reg_offs = PWRONCR_OFFS;
@@ -162,3 +183,281 @@ void __iomem *rcar_sysc_init(phys_addr_t base)
 
 	return rcar_sysc_base;
 }
+
+#ifndef CONFIG_ARCH_SHMOBILE_LEGACY
+struct rcar_pm_domain {
+	struct generic_pm_domain genpd;
+	struct dev_power_governor *gov;
+	struct rcar_sysc_ch ch;
+	unsigned busy:1;		/* Set if always -EBUSY */
+	unsigned cpu:1;			/* Set if domain contains CPU */
+	char name[0];
+};
+
+static inline struct rcar_pm_domain *to_rcar_pd(struct generic_pm_domain *d)
+{
+	return container_of(d, struct rcar_pm_domain, genpd);
+}
+
+static bool rcar_pd_active_wakeup(struct device *dev)
+{
+	return true;
+}
+
+static int rcar_pd_power_down(struct generic_pm_domain *genpd)
+{
+	struct rcar_pm_domain *rcar_pd = to_rcar_pd(genpd);
+
+	pr_debug("%s: %s\n", __func__, genpd->name);
+
+	if (rcar_pd->busy) {
+		pr_debug("%s: %s busy\n", __func__, genpd->name);
+		return -EBUSY;
+	}
+
+	return rcar_sysc_power_down(&rcar_pd->ch);
+}
+
+static int rcar_pd_power_up(struct generic_pm_domain *genpd)
+{
+	pr_debug("%s: %s\n", __func__, genpd->name);
+	return rcar_sysc_power_up(&to_rcar_pd(genpd)->ch);
+}
+
+static void rcar_init_pm_domain(struct rcar_pm_domain *rcar_pd)
+{
+	struct generic_pm_domain *genpd = &rcar_pd->genpd;
+	struct dev_power_governor *gov = rcar_pd->gov;
+
+	pm_genpd_init(genpd, gov ? : &simple_qos_governor, false);
+	genpd->dev_ops.active_wakeup	= rcar_pd_active_wakeup;
+	genpd->power_off		= rcar_pd_power_down;
+	genpd->power_on			= rcar_pd_power_up;
+
+	if (rcar_sysc_power_is_off(&rcar_pd->ch))
+		rcar_sysc_power_up(&rcar_pd->ch);
+}
+
+enum pd_types {
+	PD_NORMAL,
+	PD_CPU,
+	PD_SCU,
+};
+
+#define MAX_NUM_SPECIAL_PDS	16
+
+static struct special_pd {
+	struct device_node *pd;
+	enum pd_types type;
+} special_pds[MAX_NUM_SPECIAL_PDS] __initdata;
+
+static unsigned int num_special_pds __initdata;
+
+static void __init add_special_pd(struct device_node *np, enum pd_types type)
+{
+	unsigned int i;
+	struct device_node *pd;
+
+	pd = of_parse_phandle(np, "power-domains", 0);
+	if (!pd)
+		return;
+
+	for (i = 0; i < num_special_pds; i++)
+		if (pd == special_pds[i].pd && type == special_pds[i].type) {
+			of_node_put(pd);
+			return;
+		}
+
+	if (num_special_pds == ARRAY_SIZE(special_pds)) {
+		pr_warn("Too many special PM domains\n");
+		of_node_put(pd);
+		return;
+	}
+
+	pr_debug("Special PM domain %s type %d for %s\n", pd->name, type,
+		 np->full_name);
+
+	special_pds[num_special_pds].pd = pd;
+	special_pds[num_special_pds].type = type;
+	num_special_pds++;
+}
+
+static void __init get_special_pds(void)
+{
+	struct device_node *cpu, *scu;
+
+	/* PM domains containing CPUs */
+	for_each_node_by_type(cpu, "cpu") {
+		add_special_pd(cpu, PD_CPU);
+
+		/* SCU, represented by an L2 node */
+		scu = of_parse_phandle(cpu, "next-level-cache", 0);
+		if (scu) {
+			add_special_pd(scu, PD_SCU);
+			of_node_put(scu);
+		}
+	}
+}
+
+static void __init put_special_pds(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < num_special_pds; i++)
+		of_node_put(special_pds[i].pd);
+}
+
+static enum pd_types __init pd_type(const struct device_node *pd)
+{
+	unsigned int i;
+
+	for (i = 0; i < num_special_pds; i++)
+		if (pd == special_pds[i].pd)
+			return special_pds[i].type;
+
+	return PD_NORMAL;
+}
+
+static void __init rcar_setup_pm_domain(struct device_node *np,
+					struct rcar_pm_domain *pd)
+{
+	const char *name = pd->genpd.name;
+
+	switch (pd_type(np)) {
+	case 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 CPU\n", name);
+		pd->gov = &pm_domain_always_on_gov;
+		pd->busy = true;
+		pd->cpu = true;
+		break;
+
+	case 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 SCU\n", name);
+		pd->gov = &pm_domain_always_on_gov;
+		pd->busy = true;
+		break;
+
+	case PD_NORMAL:
+		break;
+	}
+
+	rcar_init_pm_domain(pd);
+}
+
+static int __init rcar_add_pm_domains(struct device_node *parent,
+				      struct generic_pm_domain *genpd_parent,
+				      u32 *syscier)
+{
+	struct device_node *np;
+
+	for_each_child_of_node(parent, np) {
+		struct rcar_pm_domain *pd;
+		u32 reg[2];
+		int n;
+
+		if (of_property_read_u32_array(np, "reg", reg, ARRAY_SIZE(reg)))
+			return -EINVAL;
+
+		*syscier |= BIT(reg[0]);
+
+		if (!IS_ENABLED(CONFIG_PM)) {
+			/* Just continue parsing "reg" to update *syscier */
+			rcar_add_pm_domains(np, NULL, syscier);
+			continue;
+		}
+
+		n = snprintf(NULL, 0, "%s@%u", np->name, reg[0]) + 1;
+
+		pd = kzalloc(sizeof(*pd) + n, GFP_KERNEL);
+		if (!pd)
+			return -ENOMEM;
+
+		snprintf(pd->name, n, "%s@%u", np->name, reg[0]);
+		pd->genpd.name = pd->name;
+		pd->ch.chan_offs = reg[1] & ~31;
+		pd->ch.chan_bit = reg[1] & 31;
+		pd->ch.isr_bit = reg[0];
+
+		rcar_setup_pm_domain(np, pd);
+		if (genpd_parent)
+			pm_genpd_add_subdomain(genpd_parent, &pd->genpd);
+		of_genpd_add_provider_simple(np, &pd->genpd);
+
+		rcar_add_pm_domains(np, &pd->genpd, syscier);
+	}
+	return 0;
+}
+
+static const struct of_device_id rcar_sysc_matches[] = {
+	{ .compatible = "renesas,sysc-r8a7779", .data = (void *)1 },
+	/* Default is R-Car Gen2 */
+	{ .compatible = "renesas,sysc-rcar", .data = (void *)2 },
+	{ /* sentinel */ }
+};
+
+static int __init rcar_init_pm_domains(void)
+{
+	const struct of_device_id *match;
+	struct device_node *np, *pmd;
+	bool scanned = false;
+	void __iomem *base;
+	int ret = 0;
+
+	for_each_matching_node_and_match(np, rcar_sysc_matches, &match) {
+		u32 syscier = 0;
+
+		rcar_gen = (unsigned int)match->data;
+
+		base = of_iomap(np, 0);
+		if (!base) {
+			pr_warn("%s cannot map reg 0\n", np->full_name);
+			continue;
+		}
+
+		rcar_sysc_base = base;	// FIXME conflicts with rcar_sysc_init()
+
+		pmd = of_get_child_by_name(np, "pm-domains");
+		if (!pmd) {
+			pr_warn("%s lacks pm-domains node\n", np->full_name);
+			continue;
+		}
+
+		if (!scanned) {
+			/* Find PM domains containing special blocks */
+			get_special_pds();
+			scanned = true;
+		}
+
+		ret = rcar_add_pm_domains(pmd, NULL, &syscier);
+		of_node_put(pmd);
+		if (ret) {
+			of_node_put(np);
+			break;
+		}
+
+		/*
+		 * Enable all interrupt sources, but do not use interrupt
+		 * handler
+		 */
+		pr_debug("%s: syscier = 0x%08x\n", np->full_name, syscier);
+		iowrite32(syscier, rcar_sysc_base + SYSCIER);
+		iowrite32(0, rcar_sysc_base + SYSCIMR);
+	}
+
+	put_special_pds();
+
+	return ret;
+}
+
+core_initcall(rcar_init_pm_domains);
+
+#endif /* !CONFIG_ARCH_SHMOBILE_LEGACY */
-- 
1.9.1

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