drivers/soc/bcm/brcmstb/biuctrl.c

/*
 * Broadcom STB SoCs Bus Unit Interface controls
 *
 * Copyright (C) 2015, Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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.
 */

#define pr_fmt(fmt)	"brcmstb: " KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/io.h>
#include <linux/of_address.h>
#include <linux/syscore_ops.h>
#include <linux/soc/brcmstb/brcmstb.h>

#define CPU_CREDIT_REG_OFFSET			0x184
#define  CPU_CREDIT_REG_MCPx_WR_PAIRING_EN_MASK	0x70000000

static void __iomem *cpubiuctrl_base;
static bool mcp_wr_pairing_en;

static int __init mcp_write_pairing_set(void)
{
	u32 creds = 0;

	if (!cpubiuctrl_base)
		return -1;

	creds = readl_relaxed(cpubiuctrl_base + CPU_CREDIT_REG_OFFSET);
	if (mcp_wr_pairing_en) {
		pr_info("MCP: Enabling write pairing\n");
		writel_relaxed(creds | CPU_CREDIT_REG_MCPx_WR_PAIRING_EN_MASK,
			     cpubiuctrl_base + CPU_CREDIT_REG_OFFSET);
	} else if (creds & CPU_CREDIT_REG_MCPx_WR_PAIRING_EN_MASK) {
		pr_info("MCP: Disabling write pairing\n");
		writel_relaxed(creds & ~CPU_CREDIT_REG_MCPx_WR_PAIRING_EN_MASK,
				cpubiuctrl_base + CPU_CREDIT_REG_OFFSET);
	} else {
		pr_info("MCP: Write pairing already disabled\n");
	}

	return 0;
}

static int __init setup_hifcpubiuctrl_regs(void)
{
	struct device_node *np;
	int ret = 0;

	np = of_find_compatible_node(NULL, NULL, "brcm,brcmstb-cpu-biu-ctrl");
	if (!np) {
		pr_err("missing BIU control node\n");
		return -ENODEV;
	}

	cpubiuctrl_base = of_iomap(np, 0);
	if (!cpubiuctrl_base) {
		pr_err("failed to remap BIU control base\n");
		ret = -ENOMEM;
		goto out;
	}

	mcp_wr_pairing_en = of_property_read_bool(np, "brcm,write-pairing");
out:
	of_node_put(np);
	return ret;
}

#ifdef CONFIG_PM_SLEEP
static u32 cpu_credit_reg_dump;  /* for save/restore */

static int brcmstb_cpu_credit_reg_suspend(void)
{
	if (cpubiuctrl_base)
		cpu_credit_reg_dump =
			readl_relaxed(cpubiuctrl_base + CPU_CREDIT_REG_OFFSET);
	return 0;
}

static void brcmstb_cpu_credit_reg_resume(void)
{
	if (cpubiuctrl_base)
		writel_relaxed(cpu_credit_reg_dump,
				cpubiuctrl_base + CPU_CREDIT_REG_OFFSET);
}

static struct syscore_ops brcmstb_cpu_credit_syscore_ops = {
	.suspend = brcmstb_cpu_credit_reg_suspend,
	.resume = brcmstb_cpu_credit_reg_resume,
};
#endif


void __init brcmstb_biuctrl_init(void)
{
	int ret;

	setup_hifcpubiuctrl_regs();

	ret = mcp_write_pairing_set();
	if (ret) {
		pr_err("MCP: Unable to disable write pairing!\n");
		return;
	}

#ifdef CONFIG_PM_SLEEP
	register_syscore_ops(&brcmstb_cpu_credit_syscore_ops);
#endif
}