ARM: dove: create a proper PMU driver for power domains, PMU IRQs and resets

The PMU device contains an interrupt controller, power control and
resets.  The interrupt controller is a little sub-standard in that
there is no race free way to clear down pending interrupts, so we try
to avoid problems by reducing the window as much as possible, and
clearing as infrequently as possible.

The interrupt support is implemented using an IRQ domain, and the
parent interrupt referenced in the standard DT way.

The power domains and reset support is closely related - there is a
defined sequence for powering down a domain which is tightly coupled
with asserting the reset.  Hence, it makes sense to group these two
together, and in order to avoid any locking contention disrupting this
sequence, we avoid the use of syscon or regmap.

This patch adds the core PMU driver: power domains must be defined in
the DT file in order to make use of them.  The reset controller can
be referenced in the standard way for reset controllers.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/mach-mvebu/Kconfig

@@ -96,6 +96,7 @@ config MACH_DOVE
 	select MACH_MVEBU_ANY
 	select ORION_IRQCHIP
 	select ORION_TIMER
+	select PM_GENERIC_DOMAINS if PM
 	select PINCTRL_DOVE
 	help
 	  Say 'Y' here if you want your kernel to support the

arch/arm/mach-mvebu/dove.c

@@ -12,6 +12,7 @@
 #include <linux/mbus.h>
 #include <linux/of.h>
 #include <linux/of_platform.h>
+#include <linux/soc/dove/pmu.h>
 #include <asm/hardware/cache-tauros2.h>
 #include <asm/mach/arch.h>
 #include "common.h"
@@ -24,6 +25,7 @@ static void __init dove_init(void)
 	tauros2_init(0);
 #endif
 	BUG_ON(mvebu_mbus_dt_init(false));
+	dove_init_pmu();
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
 }
 

drivers/soc/Makefile

@@ -2,6 +2,7 @@
 # Makefile for the Linux Kernel SOC specific device drivers.
 #
 
+obj-$(CONFIG_MACH_DOVE)		+= dove/
 obj-$(CONFIG_ARCH_MEDIATEK)	+= mediatek/
 obj-$(CONFIG_ARCH_QCOM)		+= qcom/
 obj-$(CONFIG_ARCH_SUNXI)	+= sunxi/

drivers/soc/dove/Makefile

+obj-y		+= pmu.o

drivers/soc/dove/pmu.c

+/*
+ * Marvell Dove PMU support
+ */
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/reset.h>
+#include <linux/reset-controller.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/soc/dove/pmu.h>
+#include <linux/spinlock.h>
+
+#define NR_PMU_IRQS		7
+
+#define PMC_SW_RST		0x30
+#define PMC_IRQ_CAUSE		0x50
+#define PMC_IRQ_MASK		0x54
+
+#define PMU_PWR			0x10
+#define PMU_ISO			0x58
+
+struct pmu_data {
+	spinlock_t lock;
+	struct device_node *of_node;
+	void __iomem *pmc_base;
+	void __iomem *pmu_base;
+	struct irq_chip_generic *irq_gc;
+	struct irq_domain *irq_domain;
+#ifdef CONFIG_RESET_CONTROLLER
+	struct reset_controller_dev reset;
+#endif
+};
+
+/*
+ * The PMU contains a register to reset various subsystems within the
+ * SoC.  Export this as a reset controller.
+ */
+#ifdef CONFIG_RESET_CONTROLLER
+#define rcdev_to_pmu(rcdev) container_of(rcdev, struct pmu_data, reset)
+
+static int pmu_reset_reset(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct pmu_data *pmu = rcdev_to_pmu(rc);
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+	val = readl_relaxed(pmu->pmc_base + PMC_SW_RST);
+	writel_relaxed(val & ~BIT(id), pmu->pmc_base + PMC_SW_RST);
+	writel_relaxed(val | BIT(id), pmu->pmc_base + PMC_SW_RST);
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static int pmu_reset_assert(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct pmu_data *pmu = rcdev_to_pmu(rc);
+	unsigned long flags;
+	u32 val = ~BIT(id);
+
+	spin_lock_irqsave(&pmu->lock, flags);
+	val &= readl_relaxed(pmu->pmc_base + PMC_SW_RST);
+	writel_relaxed(val, pmu->pmc_base + PMC_SW_RST);
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static int pmu_reset_deassert(struct reset_controller_dev *rc, unsigned long id)
+{
+	struct pmu_data *pmu = rcdev_to_pmu(rc);
+	unsigned long flags;
+	u32 val = BIT(id);
+
+	spin_lock_irqsave(&pmu->lock, flags);
+	val |= readl_relaxed(pmu->pmc_base + PMC_SW_RST);
+	writel_relaxed(val, pmu->pmc_base + PMC_SW_RST);
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static struct reset_control_ops pmu_reset_ops = {
+	.reset = pmu_reset_reset,
+	.assert = pmu_reset_assert,
+	.deassert = pmu_reset_deassert,
+};
+
+static struct reset_controller_dev pmu_reset __initdata = {
+	.ops = &pmu_reset_ops,
+	.owner = THIS_MODULE,
+	.nr_resets = 32,
+};
+
+static void __init pmu_reset_init(struct pmu_data *pmu)
+{
+	int ret;
+
+	pmu->reset = pmu_reset;
+	pmu->reset.of_node = pmu->of_node;
+
+	ret = reset_controller_register(&pmu->reset);
+	if (ret)
+		pr_err("pmu: %s failed: %d\n", "reset_controller_register", ret);
+}
+#else
+static void __init pmu_reset_init(struct pmu_data *pmu)
+{
+}
+#endif
+
+struct pmu_domain {
+	struct pmu_data *pmu;
+	u32 pwr_mask;
+	u32 rst_mask;
+	u32 iso_mask;
+	struct generic_pm_domain base;
+};
+
+#define to_pmu_domain(dom) container_of(dom, struct pmu_domain, base)
+
+/*
+ * This deals with the "old" Marvell sequence of bringing a power domain
+ * down/up, which is: apply power, release reset, disable isolators.
+ *
+ * Later devices apparantly use a different sequence: power up, disable
+ * isolators, assert repair signal, enable SRMA clock, enable AXI clock,
+ * enable module clock, deassert reset.
+ *
+ * Note: reading the assembly, it seems that the IO accessors have an
+ * unfortunate side-effect - they cause memory already read into registers
+ * for the if () to be re-read for the bit-set or bit-clear operation.
+ * The code is written to avoid this.
+ */
+static int pmu_domain_power_off(struct generic_pm_domain *domain)
+{
+	struct pmu_domain *pmu_dom = to_pmu_domain(domain);
+	struct pmu_data *pmu = pmu_dom->pmu;
+	unsigned long flags;
+	unsigned int val;
+	void __iomem *pmu_base = pmu->pmu_base;
+	void __iomem *pmc_base = pmu->pmc_base;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	/* Enable isolators */
+	if (pmu_dom->iso_mask) {
+		val = ~pmu_dom->iso_mask;
+		val &= readl_relaxed(pmu_base + PMU_ISO);
+		writel_relaxed(val, pmu_base + PMU_ISO);
+	}
+
+	/* Reset unit */
+	if (pmu_dom->rst_mask) {
+		val = ~pmu_dom->rst_mask;
+		val &= readl_relaxed(pmc_base + PMC_SW_RST);
+		writel_relaxed(val, pmc_base + PMC_SW_RST);
+	}
+
+	/* Power down */
+	val = readl_relaxed(pmu_base + PMU_PWR) | pmu_dom->pwr_mask;
+	writel_relaxed(val, pmu_base + PMU_PWR);
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static int pmu_domain_power_on(struct generic_pm_domain *domain)
+{
+	struct pmu_domain *pmu_dom = to_pmu_domain(domain);
+	struct pmu_data *pmu = pmu_dom->pmu;
+	unsigned long flags;
+	unsigned int val;
+	void __iomem *pmu_base = pmu->pmu_base;
+	void __iomem *pmc_base = pmu->pmc_base;
+
+	spin_lock_irqsave(&pmu->lock, flags);
+
+	/* Power on */
+	val = ~pmu_dom->pwr_mask & readl_relaxed(pmu_base + PMU_PWR);
+	writel_relaxed(val, pmu_base + PMU_PWR);
+
+	/* Release reset */
+	if (pmu_dom->rst_mask) {
+		val = pmu_dom->rst_mask;
+		val |= readl_relaxed(pmc_base + PMC_SW_RST);
+		writel_relaxed(val, pmc_base + PMC_SW_RST);
+	}
+
+	/* Disable isolators */
+	if (pmu_dom->iso_mask) {
+		val = pmu_dom->iso_mask;
+		val |= readl_relaxed(pmu_base + PMU_ISO);
+		writel_relaxed(val, pmu_base + PMU_ISO);
+	}
+
+	spin_unlock_irqrestore(&pmu->lock, flags);
+
+	return 0;
+}
+
+static void __pmu_domain_register(struct pmu_domain *domain,
+	struct device_node *np)
+{
+	unsigned int val = readl_relaxed(domain->pmu->pmu_base + PMU_PWR);
+
+	domain->base.power_off = pmu_domain_power_off;
+	domain->base.power_on = pmu_domain_power_on;
+
+	pm_genpd_init(&domain->base, NULL, !(val & domain->pwr_mask));
+
+	if (np)
+		of_genpd_add_provider_simple(np, &domain->base);
+}
+
+/* PMU IRQ controller */
+static void pmu_irq_handler(unsigned int irq, struct irq_desc *desc)
+{
+	struct pmu_data *pmu = irq_get_handler_data(irq);
+	struct irq_chip_generic *gc = pmu->irq_gc;
+	struct irq_domain *domain = pmu->irq_domain;
+	void __iomem *base = gc->reg_base;
+	u32 stat = readl_relaxed(base + PMC_IRQ_CAUSE) & gc->mask_cache;
+	u32 done = ~0;
+
+	if (stat == 0) {
+		handle_bad_irq(irq, desc);
+		return;
+	}
+
+	while (stat) {
+		u32 hwirq = fls(stat) - 1;
+
+		stat &= ~(1 << hwirq);
+		done &= ~(1 << hwirq);
+
+		generic_handle_irq(irq_find_mapping(domain, hwirq));
+	}
+
+	/*
+	 * The PMU mask register is not RW0C: it is RW.  This means that
+	 * the bits take whatever value is written to them; if you write
+	 * a '1', you will set the interrupt.
+	 *
+	 * Unfortunately this means there is NO race free way to clear
+	 * these interrupts.
+	 *
+	 * So, let's structure the code so that the window is as small as
+	 * possible.
+	 */
+	irq_gc_lock(gc);
+	done &= readl_relaxed(base + PMC_IRQ_CAUSE);
+	writel_relaxed(done, base + PMC_IRQ_CAUSE);
+	irq_gc_unlock(gc);
+}
+
+static int __init dove_init_pmu_irq(struct pmu_data *pmu, int irq)
+{
+	const char *name = "pmu_irq";
+	struct irq_chip_generic *gc;
+	struct irq_domain *domain;
+	int ret;
+
+	/* mask and clear all interrupts */
+	writel(0, pmu->pmc_base + PMC_IRQ_MASK);
+	writel(0, pmu->pmc_base + PMC_IRQ_CAUSE);
+
+	domain = irq_domain_add_linear(pmu->of_node, NR_PMU_IRQS,
+				       &irq_generic_chip_ops, NULL);
+	if (!domain) {
+		pr_err("%s: unable to add irq domain\n", name);
+		return -ENOMEM;
+	}
+
+	ret = irq_alloc_domain_generic_chips(domain, NR_PMU_IRQS, 1, name,
+					     handle_level_irq,
+					     IRQ_NOREQUEST | IRQ_NOPROBE, 0,
+					     IRQ_GC_INIT_MASK_CACHE);
+	if (ret) {
+		pr_err("%s: unable to alloc irq domain gc: %d\n", name, ret);
+		irq_domain_remove(domain);
+		return ret;
+	}
+
+	gc = irq_get_domain_generic_chip(domain, 0);
+	gc->reg_base = pmu->pmc_base;
+	gc->chip_types[0].regs.mask = PMC_IRQ_MASK;
+	gc->chip_types[0].chip.irq_mask = irq_gc_mask_clr_bit;
+	gc->chip_types[0].chip.irq_unmask = irq_gc_mask_set_bit;
+
+	pmu->irq_domain = domain;
+	pmu->irq_gc = gc;
+
+	irq_set_handler_data(irq, pmu);
+	irq_set_chained_handler(irq, pmu_irq_handler);
+
+	return 0;
+}
+
+/*
+ * pmu: power-manager@d0000 {
+ *	compatible = "marvell,dove-pmu";
+ *	reg = <0xd0000 0x8000> <0xd8000 0x8000>;
+ *	interrupts = <33>;
+ *	interrupt-controller;
+ *	#reset-cells = 1;
+ *	vpu_domain: vpu-domain {
+ *		#power-domain-cells = <0>;
+ *		marvell,pmu_pwr_mask = <0x00000008>;
+ *		marvell,pmu_iso_mask = <0x00000001>;
+ *		resets = <&pmu 16>;
+ *	};
+ *	gpu_domain: gpu-domain {
+ *		#power-domain-cells = <0>;
+ *		marvell,pmu_pwr_mask = <0x00000004>;
+ *		marvell,pmu_iso_mask = <0x00000002>;
+ *		resets = <&pmu 18>;
+ *	};
+ * };
+ */
+int __init dove_init_pmu(void)
+{
+	struct device_node *np_pmu, *domains_node, *np;
+	struct pmu_data *pmu;
+	int ret, parent_irq;
+
+	/* Lookup the PMU node */
+	np_pmu = of_find_compatible_node(NULL, NULL, "marvell,dove-pmu");
+	if (!np_pmu)
+		return 0;
+
+	domains_node = of_get_child_by_name(np_pmu, "domains");
+	if (!domains_node) {
+		pr_err("%s: failed to find domains sub-node\n", np_pmu->name);
+		return 0;
+	}
+
+	pmu = kzalloc(sizeof(*pmu), GFP_KERNEL);
+	if (!pmu)
+		return -ENOMEM;
+
+	spin_lock_init(&pmu->lock);
+	pmu->of_node = np_pmu;
+	pmu->pmc_base = of_iomap(pmu->of_node, 0);
+	pmu->pmu_base = of_iomap(pmu->of_node, 1);
+	if (!pmu->pmc_base || !pmu->pmu_base) {
+		pr_err("%s: failed to map PMU\n", np_pmu->name);
+		iounmap(pmu->pmu_base);
+		iounmap(pmu->pmc_base);
+		kfree(pmu);
+		return -ENOMEM;
+	}
+
+	pmu_reset_init(pmu);
+
+	for_each_available_child_of_node(domains_node, np) {
+		struct of_phandle_args args;
+		struct pmu_domain *domain;
+
+		domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+		if (!domain)
+			break;
+
+		domain->pmu = pmu;
+		domain->base.name = kstrdup(np->name, GFP_KERNEL);
+		if (!domain->base.name) {
+			kfree(domain);
+			break;
+		}
+
+		of_property_read_u32(np, "marvell,pmu_pwr_mask",
+				     &domain->pwr_mask);
+		of_property_read_u32(np, "marvell,pmu_iso_mask",
+				     &domain->iso_mask);
+
+		/*
+		 * We parse the reset controller property directly here
+		 * to ensure that we can operate when the reset controller
+		 * support is not configured into the kernel.
+		 */
+		ret = of_parse_phandle_with_args(np, "resets", "#reset-cells",
+						 0, &args);
+		if (ret == 0) {
+			if (args.np == pmu->of_node)
+				domain->rst_mask = BIT(args.args[0]);
+			of_node_put(args.np);
+		}
+
+		__pmu_domain_register(domain, np);
+	}
+	pm_genpd_poweroff_unused();
+
+	/* Loss of the interrupt controller is not a fatal error. */
+	parent_irq = irq_of_parse_and_map(pmu->of_node, 0);
+	if (!parent_irq) {
+		pr_err("%s: no interrupt specified\n", np_pmu->name);
+	} else {
+		ret = dove_init_pmu_irq(pmu, parent_irq);
+		if (ret)
+			pr_err("dove_init_pmu_irq() failed: %d\n", ret);
+	}
+
+	return 0;
+}

include/linux/soc/dove/pmu.h

+#ifndef LINUX_SOC_DOVE_PMU_H
+#define LINUX_SOC_DOVE_PMU_H
+
+int dove_init_pmu(void);
+
+#endif