ARM: meson: Add SMP bringup code for Meson8 and Meson8b

This adds the necessary SMP-operations and startup code to use the
additional cores on the Amlogic Meson8/Meson8m2 (both are using the same
sequence) and Meson8b (using a slightly difference sequence) SoCs.

Signed-off-by: Carlo Caione <carlo@endlessm.com>
[add Meson8/Meson8m2 support and allow taking CPU cores offline as well]
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>

Signed-off-by: Kevin Hilman <khilman@baylibre.com>

3 files changed, 442 insertions, 0 deletions

diff --git a/arch/arm/mach-meson/Kconfig b/arch/arm/mach-meson/Kconfig
index ee30511849ca..a0c64762d961 100644
--- a/arch/arm/mach-meson/Kconfig
+++ b/arch/arm/mach-meson/Kconfig
@@ -9,6 +9,7 @@ menuconfig ARCH_MESON
 	select PINCTRL_MESON
 	select COMMON_CLK
 	select COMMON_CLK_AMLOGIC
+	select HAVE_ARM_SCU if SMP
 
 if ARCH_MESON
 
diff --git a/arch/arm/mach-meson/Makefile b/arch/arm/mach-meson/Makefile
index 9d7380eeeedd..bc26c85a7e8f 100644
--- a/arch/arm/mach-meson/Makefile
+++ b/arch/arm/mach-meson/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_ARCH_MESON) += meson.o
+obj-$(CONFIG_SMP) += platsmp.o
diff --git a/arch/arm/mach-meson/platsmp.c b/arch/arm/mach-meson/platsmp.c
new file mode 100644
index 000000000000..2555f9056a33
--- /dev/null
+++ b/arch/arm/mach-meson/platsmp.c
@@ -0,0 +1,440 @@
+/*
+ * Copyright (C) 2015 Carlo Caione <carlo@endlessm.com>
+ * Copyright (C) 2017 Martin Blumenstingl <martin.blumenstingl@googlemail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+#include <linux/smp.h>
+#include <linux/mfd/syscon.h>
+
+#include <asm/cacheflush.h>
+#include <asm/cp15.h>
+#include <asm/smp_scu.h>
+#include <asm/smp_plat.h>
+
+#define MESON_SMP_SRAM_CPU_CTRL_REG		(0x00)
+#define MESON_SMP_SRAM_CPU_CTRL_ADDR_REG(c)	(0x04 + ((c - 1) << 2))
+
+#define MESON_CPU_AO_RTI_PWR_A9_CNTL0		(0x00)
+#define MESON_CPU_AO_RTI_PWR_A9_CNTL1		(0x04)
+#define MESON_CPU_AO_RTI_PWR_A9_MEM_PD0		(0x14)
+
+#define MESON_CPU_PWR_A9_CNTL0_M(c)		(0x03 << ((c * 2) + 16))
+#define MESON_CPU_PWR_A9_CNTL1_M(c)		(0x03 << ((c + 1) << 1))
+#define MESON_CPU_PWR_A9_MEM_PD0_M(c)		(0x0f << (32 - (c * 4)))
+#define MESON_CPU_PWR_A9_CNTL1_ST(c)		(0x01 << (c + 16))
+
+static void __iomem *sram_base;
+static void __iomem *scu_base;
+static struct regmap *pmu;
+
+static struct reset_control *meson_smp_get_core_reset(int cpu)
+{
+	struct device_node *np = of_get_cpu_node(cpu, 0);
+
+	return of_reset_control_get_exclusive(np, NULL);
+}
+
+static void meson_smp_set_cpu_ctrl(int cpu, bool on_off)
+{
+	u32 val = readl(sram_base + MESON_SMP_SRAM_CPU_CTRL_REG);
+
+	if (on_off)
+		val |= BIT(cpu);
+	else
+		val &= ~BIT(cpu);
+
+	/* keep bit 0 always enabled */
+	val |= BIT(0);
+
+	writel(val, sram_base + MESON_SMP_SRAM_CPU_CTRL_REG);
+}
+
+static void __init meson_smp_prepare_cpus(const char *scu_compatible,
+					  const char *pmu_compatible,
+					  const char *sram_compatible)
+{
+	static struct device_node *node;
+
+	/* SMP SRAM */
+	node = of_find_compatible_node(NULL, NULL, sram_compatible);
+	if (!node) {
+		pr_err("Missing SRAM node\n");
+		return;
+	}
+
+	sram_base = of_iomap(node, 0);
+	if (!sram_base) {
+		pr_err("Couldn't map SRAM registers\n");
+		return;
+	}
+
+	/* PMU */
+	pmu = syscon_regmap_lookup_by_compatible(pmu_compatible);
+	if (IS_ERR(pmu)) {
+		pr_err("Couldn't map PMU registers\n");
+		return;
+	}
+
+	/* SCU */
+	node = of_find_compatible_node(NULL, NULL, scu_compatible);
+	if (!node) {
+		pr_err("Missing SCU node\n");
+		return;
+	}
+
+	scu_base = of_iomap(node, 0);
+	if (!scu_base) {
+		pr_err("Couln't map SCU registers\n");
+		return;
+	}
+
+	scu_enable(scu_base);
+}
+
+static void __init meson8b_smp_prepare_cpus(unsigned int max_cpus)
+{
+	meson_smp_prepare_cpus("arm,cortex-a5-scu", "amlogic,meson8b-pmu",
+			       "amlogic,meson8b-smp-sram");
+}
+
+static void __init meson8_smp_prepare_cpus(unsigned int max_cpus)
+{
+	meson_smp_prepare_cpus("arm,cortex-a9-scu", "amlogic,meson8-pmu",
+			       "amlogic,meson8-smp-sram");
+}
+
+static void meson_smp_begin_secondary_boot(unsigned int cpu)
+{
+	/*
+	 * Set the entry point before powering on the CPU through the SCU. This
+	 * is needed if the CPU is in "warm" state (= after rebooting the
+	 * system without power-cycling, or when taking the CPU offline and
+	 * then taking it online again.
+	 */
+	writel(__pa_symbol(secondary_startup),
+	       sram_base + MESON_SMP_SRAM_CPU_CTRL_ADDR_REG(cpu));
+
+	/*
+	 * SCU Power on CPU (needs to be done before starting the CPU,
+	 * otherwise the secondary CPU will not start).
+	 */
+	scu_cpu_power_enable(scu_base, cpu);
+}
+
+static int meson_smp_finalize_secondary_boot(unsigned int cpu)
+{
+	unsigned long timeout;
+
+	timeout = jiffies + (10 * HZ);
+	while (readl(sram_base + MESON_SMP_SRAM_CPU_CTRL_ADDR_REG(cpu))) {
+		if (!time_before(jiffies, timeout)) {
+			pr_err("Timeout while waiting for CPU%d status\n",
+			       cpu);
+			return -ETIMEDOUT;
+		}
+	}
+
+	writel(__pa_symbol(secondary_startup),
+	       sram_base + MESON_SMP_SRAM_CPU_CTRL_ADDR_REG(cpu));
+
+	meson_smp_set_cpu_ctrl(cpu, true);
+
+	return 0;
+}
+
+static int meson8_smp_boot_secondary(unsigned int cpu,
+				     struct task_struct *idle)
+{
+	struct reset_control *rstc;
+	int ret;
+
+	rstc = meson_smp_get_core_reset(cpu);
+	if (IS_ERR(rstc)) {
+		pr_err("Couldn't get the reset controller for CPU%d\n", cpu);
+		return PTR_ERR(rstc);
+	}
+
+	meson_smp_begin_secondary_boot(cpu);
+
+	/* Reset enable */
+	ret = reset_control_assert(rstc);
+	if (ret) {
+		pr_err("Failed to assert CPU%d reset\n", cpu);
+		goto out;
+	}
+
+	/* CPU power ON */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL1,
+				 MESON_CPU_PWR_A9_CNTL1_M(cpu), 0);
+	if (ret < 0) {
+		pr_err("Couldn't wake up CPU%d\n", cpu);
+		goto out;
+	}
+
+	udelay(10);
+
+	/* Isolation disable */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0, BIT(cpu),
+				 0);
+	if (ret < 0) {
+		pr_err("Error when disabling isolation of CPU%d\n", cpu);
+		goto out;
+	}
+
+	/* Reset disable */
+	ret = reset_control_deassert(rstc);
+	if (ret) {
+		pr_err("Failed to de-assert CPU%d reset\n", cpu);
+		goto out;
+	}
+
+	ret = meson_smp_finalize_secondary_boot(cpu);
+	if (ret)
+		goto out;
+
+out:
+	reset_control_put(rstc);
+
+	return 0;
+}
+
+static int meson8b_smp_boot_secondary(unsigned int cpu,
+				     struct task_struct *idle)
+{
+	struct reset_control *rstc;
+	int ret;
+	u32 val;
+
+	rstc = meson_smp_get_core_reset(cpu);
+	if (IS_ERR(rstc)) {
+		pr_err("Couldn't get the reset controller for CPU%d\n", cpu);
+		return PTR_ERR(rstc);
+	}
+
+	meson_smp_begin_secondary_boot(cpu);
+
+	/* CPU power UP */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0,
+				 MESON_CPU_PWR_A9_CNTL0_M(cpu), 0);
+	if (ret < 0) {
+		pr_err("Couldn't power up CPU%d\n", cpu);
+		goto out;
+	}
+
+	udelay(5);
+
+	/* Reset enable */
+	ret = reset_control_assert(rstc);
+	if (ret) {
+		pr_err("Failed to assert CPU%d reset\n", cpu);
+		goto out;
+	}
+
+	/* Memory power UP */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_MEM_PD0,
+				 MESON_CPU_PWR_A9_MEM_PD0_M(cpu), 0);
+	if (ret < 0) {
+		pr_err("Couldn't power up the memory for CPU%d\n", cpu);
+		goto out;
+	}
+
+	/* Wake up CPU */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL1,
+				 MESON_CPU_PWR_A9_CNTL1_M(cpu), 0);
+	if (ret < 0) {
+		pr_err("Couldn't wake up CPU%d\n", cpu);
+		goto out;
+	}
+
+	udelay(10);
+
+	ret = regmap_read_poll_timeout(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL1, val,
+				       val & MESON_CPU_PWR_A9_CNTL1_ST(cpu),
+				       10, 10000);
+	if (ret) {
+		pr_err("Timeout while polling PMU for CPU%d status\n", cpu);
+		goto out;
+	}
+
+	/* Isolation disable */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0, BIT(cpu),
+				 0);
+	if (ret < 0) {
+		pr_err("Error when disabling isolation of CPU%d\n", cpu);
+		goto out;
+	}
+
+	/* Reset disable */
+	ret = reset_control_deassert(rstc);
+	if (ret) {
+		pr_err("Failed to de-assert CPU%d reset\n", cpu);
+		goto out;
+	}
+
+	ret = meson_smp_finalize_secondary_boot(cpu);
+	if (ret)
+		goto out;
+
+out:
+	reset_control_put(rstc);
+
+	return 0;
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+static void meson8_smp_cpu_die(unsigned int cpu)
+{
+	meson_smp_set_cpu_ctrl(cpu, false);
+
+	v7_exit_coherency_flush(louis);
+
+	scu_power_mode(scu_base, SCU_PM_POWEROFF);
+
+	dsb();
+	wfi();
+
+	/* we should never get here */
+	WARN_ON(1);
+}
+
+static int meson8_smp_cpu_kill(unsigned int cpu)
+{
+	int ret, power_mode;
+	unsigned long timeout;
+
+	timeout = jiffies + (50 * HZ);
+	do {
+		power_mode = scu_get_cpu_power_mode(scu_base, cpu);
+
+		if (power_mode == SCU_PM_POWEROFF)
+			break;
+
+		usleep_range(10000, 15000);
+	} while (time_before(jiffies, timeout));
+
+	if (power_mode != SCU_PM_POWEROFF) {
+		pr_err("Error while waiting for SCU power-off on CPU%d\n",
+		       cpu);
+		return -ETIMEDOUT;
+	}
+
+	msleep(30);
+
+	/* Isolation enable */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0, BIT(cpu),
+				 0x3);
+	if (ret < 0) {
+		pr_err("Error when enabling isolation for CPU%d\n", cpu);
+		return ret;
+	}
+
+	udelay(10);
+
+	/* CPU power OFF */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL1,
+				 MESON_CPU_PWR_A9_CNTL1_M(cpu), 0x3);
+	if (ret < 0) {
+		pr_err("Couldn't change sleep status of CPU%d\n", cpu);
+		return ret;
+	}
+
+	return 1;
+}
+
+static int meson8b_smp_cpu_kill(unsigned int cpu)
+{
+	int ret, power_mode, count = 5000;
+
+	do {
+		power_mode = scu_get_cpu_power_mode(scu_base, cpu);
+
+		if (power_mode == SCU_PM_POWEROFF)
+			break;
+
+		udelay(10);
+	} while (++count);
+
+	if (power_mode != SCU_PM_POWEROFF) {
+		pr_err("Error while waiting for SCU power-off on CPU%d\n",
+		       cpu);
+		return -ETIMEDOUT;
+	}
+
+	udelay(10);
+
+	/* CPU power DOWN */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0,
+				 MESON_CPU_PWR_A9_CNTL0_M(cpu), 0x3);
+	if (ret < 0) {
+		pr_err("Couldn't power down CPU%d\n", cpu);
+		return ret;
+	}
+
+	/* Isolation enable */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL0, BIT(cpu),
+				 0x3);
+	if (ret < 0) {
+		pr_err("Error when enabling isolation for CPU%d\n", cpu);
+		return ret;
+	}
+
+	udelay(10);
+
+	/* Sleep status */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_CNTL1,
+				 MESON_CPU_PWR_A9_CNTL1_M(cpu), 0x3);
+	if (ret < 0) {
+		pr_err("Couldn't change sleep status of CPU%d\n", cpu);
+		return ret;
+	}
+
+	/* Memory power DOWN */
+	ret = regmap_update_bits(pmu, MESON_CPU_AO_RTI_PWR_A9_MEM_PD0,
+				 MESON_CPU_PWR_A9_MEM_PD0_M(cpu), 0xf);
+	if (ret < 0) {
+		pr_err("Couldn't power down the memory of CPU%d\n", cpu);
+		return ret;
+	}
+
+	return 1;
+}
+#endif
+
+static struct smp_operations meson8_smp_ops __initdata = {
+	.smp_prepare_cpus	= meson8_smp_prepare_cpus,
+	.smp_boot_secondary	= meson8_smp_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_die		= meson8_smp_cpu_die,
+	.cpu_kill		= meson8_smp_cpu_kill,
+#endif
+};
+
+static struct smp_operations meson8b_smp_ops __initdata = {
+	.smp_prepare_cpus	= meson8b_smp_prepare_cpus,
+	.smp_boot_secondary	= meson8b_smp_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_die		= meson8_smp_cpu_die,
+	.cpu_kill		= meson8b_smp_cpu_kill,
+#endif
+};
+
+CPU_METHOD_OF_DECLARE(meson8_smp, "amlogic,meson8-smp", &meson8_smp_ops);
+CPU_METHOD_OF_DECLARE(meson8b_smp, "amlogic,meson8b-smp", &meson8b_smp_ops);