ARM: BCM63xx: Add secondary CPU PMB initialization sequence

The sequence to initialize a secondary CPU using the BCM63138 PMB is
extremely specific and represents much more code than any other on-chip
peripheral (AHCI, USB 3.0 or integrated Ethernet switch), as such we
keep that code local and utilize Device Tree to lookup all the resources
we need from the CPU device tree node.
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>

arch/arm/mach-bcm/bcm63xx_pmb.c

+/*
+ * Broadcom BCM63138 PMB initialization for secondary CPU(s)
+ *
+ * Copyright (C) 2015 Broadcom Corporation
+ * Author: Florian Fainelli <f.fainelli@gmail.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.
+ */
+#include <linux/kernel.h>
+#include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/reset/bcm63xx_pmb.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#include "bcm63xx_smp.h"
+
+/* ARM Control register definitions */
+#define CORE_PWR_CTRL_SHIFT	0
+#define CORE_PWR_CTRL_MASK	0x3
+#define PLL_PWR_ON		BIT(8)
+#define PLL_LDO_PWR_ON		BIT(9)
+#define PLL_CLAMP_ON		BIT(10)
+#define CPU_RESET_N(x)		BIT(13 + (x))
+#define NEON_RESET_N		BIT(15)
+#define PWR_CTRL_STATUS_SHIFT	28
+#define PWR_CTRL_STATUS_MASK	0x3
+#define PWR_DOWN_SHIFT		30
+#define PWR_DOWN_MASK		0x3
+
+/* CPU Power control register definitions */
+#define MEM_PWR_OK		BIT(0)
+#define MEM_PWR_ON		BIT(1)
+#define MEM_CLAMP_ON		BIT(2)
+#define MEM_PWR_OK_STATUS	BIT(4)
+#define MEM_PWR_ON_STATUS	BIT(5)
+#define MEM_PDA_SHIFT		8
+#define MEM_PDA_MASK		0xf
+#define  MEM_PDA_CPU_MASK	0x1
+#define  MEM_PDA_NEON_MASK	0xf
+#define CLAMP_ON		BIT(15)
+#define PWR_OK_SHIFT		16
+#define PWR_OK_MASK		0xf
+#define PWR_ON_SHIFT		20
+#define  PWR_CPU_MASK		0x03
+#define  PWR_NEON_MASK		0x01
+#define PWR_ON_MASK		0xf
+#define PWR_OK_STATUS_SHIFT	24
+#define PWR_OK_STATUS_MASK	0xf
+#define PWR_ON_STATUS_SHIFT	28
+#define PWR_ON_STATUS_MASK	0xf
+
+#define ARM_CONTROL		0x30
+#define ARM_PWR_CONTROL_BASE	0x34
+#define ARM_PWR_CONTROL(x)	(ARM_PWR_CONTROL_BASE + (x) * 0x4)
+#define ARM_NEON_L2		0x3c
+
+/* Perform a value write, then spin until the value shifted by
+ * shift is seen, masked with mask and is different from cond.
+ */
+static int bpcm_wr_rd_mask(void __iomem *master,
+			   unsigned int addr, u32 off, u32 *val,
+			   u32 shift, u32 mask, u32 cond)
+{
+	int ret;
+
+	ret = bpcm_wr(master, addr, off, *val);
+	if (ret)
+		return ret;
+
+	do {
+		ret = bpcm_rd(master, addr, off, val);
+		if (ret)
+			return ret;
+
+		cpu_relax();
+	} while (((*val >> shift) & mask) != cond);
+
+	return ret;
+}
+
+/* Global lock to serialize accesses to the PMB registers while we
+ * are bringing up the secondary CPU
+ */
+static DEFINE_SPINLOCK(pmb_lock);
+
+static int bcm63xx_pmb_get_resources(struct device_node *dn,
+				     void __iomem **base,
+				     unsigned int *cpu,
+				     unsigned int *addr)
+{
+	struct device_node *pmb_dn;
+	struct of_phandle_args args;
+	int ret;
+
+	ret = of_property_read_u32(dn, "reg", cpu);
+	if (ret) {
+		pr_err("CPU is missing a reg node\n");
+		return ret;
+	}
+
+	ret = of_parse_phandle_with_args(dn, "resets", "#reset-cells",
+					 0, &args);
+	if (ret) {
+		pr_err("CPU is missing a resets phandle\n");
+		return ret;
+	}
+
+	pmb_dn = args.np;
+	if (args.args_count != 2) {
+		pr_err("reset-controller does not conform to reset-cells\n");
+		return -EINVAL;
+	}
+
+	*base = of_iomap(args.np, 0);
+	if (!*base) {
+		pr_err("failed remapping PMB register\n");
+		return -ENOMEM;
+	}
+
+	/* We do not need the number of zones */
+	*addr = args.args[0];
+
+	return 0;
+}
+
+int bcm63xx_pmb_power_on_cpu(struct device_node *dn)
+{
+	void __iomem *base;
+	unsigned int cpu, addr;
+	unsigned long flags;
+	u32 val, ctrl;
+	int ret;
+
+	ret = bcm63xx_pmb_get_resources(dn, &base, &cpu, &addr);
+	if (ret)
+		return ret;
+
+	/* We would not know how to enable a third and greater CPU */
+	WARN_ON(cpu > 1);
+
+	spin_lock_irqsave(&pmb_lock, flags);
+
+	/* Check if the CPU is already on and save the ARM_CONTROL register
+	 * value since we will use it later for CPU de-assert once done with
+	 * the CPU-specific power sequence
+	 */
+	ret = bpcm_rd(base, addr, ARM_CONTROL, &ctrl);
+	if (ret)
+		return ret;
+
+	if (ctrl & CPU_RESET_N(cpu)) {
+		pr_info("PMB: CPU%d is already powered on\n", cpu);
+		ret = 0;
+		goto out;
+	}
+
+	/* Power on PLL */
+	ret = bpcm_rd(base, addr, ARM_PWR_CONTROL(cpu), &val);
+	if (ret)
+		goto out;
+
+	val |= (PWR_CPU_MASK << PWR_ON_SHIFT);
+
+	ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
+			PWR_ON_STATUS_SHIFT, PWR_CPU_MASK, PWR_CPU_MASK);
+	if (ret)
+		goto out;
+
+	val |= (PWR_CPU_MASK << PWR_OK_SHIFT);
+
+	ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
+			PWR_OK_STATUS_SHIFT, PWR_CPU_MASK, PWR_CPU_MASK);
+	if (ret)
+		goto out;
+
+	val &= ~CLAMP_ON;
+
+	ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
+	if (ret)
+		goto out;
+
+	/* Power on CPU<N> RAM */
+	val &= ~(MEM_PDA_MASK << MEM_PDA_SHIFT);
+
+	ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
+	if (ret)
+		goto out;
+
+	val |= MEM_PWR_ON;
+
+	ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
+			0, MEM_PWR_ON_STATUS, MEM_PWR_ON_STATUS);
+	if (ret)
+		goto out;
+
+	val |= MEM_PWR_OK;
+
+	ret = bpcm_wr_rd_mask(base, addr, ARM_PWR_CONTROL(cpu), &val,
+			0, MEM_PWR_OK_STATUS, MEM_PWR_OK_STATUS);
+	if (ret)
+		goto out;
+
+	val &= ~MEM_CLAMP_ON;
+
+	ret = bpcm_wr(base, addr, ARM_PWR_CONTROL(cpu), val);
+	if (ret)
+		goto out;
+
+	/* De-assert CPU reset */
+	ctrl |= CPU_RESET_N(cpu);
+
+	ret = bpcm_wr(base, addr, ARM_CONTROL, ctrl);
+out:
+	spin_unlock_irqrestore(&pmb_lock, flags);
+	iounmap(base);
+	return ret;
+}