/*
 * Allwinner GPU power domain support.
 *
 * Copyright (C) 2019 Allwinner Technology, Inc.
 *	fanqinghua <fanqinghua@allwinnertech.com>
 *
 * Implementation of gpu specific power domain control which is used in
 * conjunction with runtime-pm. Support for both device-tree and non-device-tree
 * based power domain support is included.
 *
 * 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.
 */

#include <linux/io.h>
#include <linux/interrupt.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/pm_domain.h>
#include <linux/clk.h>
#include <linux/regmap.h>
#include <linux/delay.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/sched.h>
#include <linux/mfd/syscon.h>

#define GPU_RSTN_REG			0x0
#define GPU_CLK_GATE_REG		0x4
#define GPU_POWEROFF_GATE_REG	0x8
#define GPU_PSWON_REG			0xC

#define GPU_PSWOFF_REG			0x10
#define GPU_PDA_OFF				0xff
#define GPU_PDB_OFF				0xff0000

#define GPU_PSW_DLY_REG			0x14
#define GPU_PDOFFCTL_DLY_REG	0x18
#define GPU_PDONCTL_DLY_REG		0x1C

#define GPU_PD_STAT_REG			0x20
#define GPU_PD_STAT_MASK		0x3
#define GPU_PD_STAT_3D			0x0
#define GPU_PD_STAT_HOST		0x1
#define GPU_PD_STAT_ALLOFF		0x2

#define PPU_CFG_REG				0x24
#define POWER_CTRL_MODE_MASK	0x3
#define POWER_CTRL_MODE_SW		0x1
#define POWER_CTRL_MODE_HW		0x2
#define PPU_POWER_ON_COMPLETE	0x10

#define PPU_STAT_REG			0x28
#define GPU_POWER_REQ			0x1
#define GPU_STAT_3D_2_HOST		0x2
#define GPU_STAT_HOST_2_3D		0x4
#define GPU_STAT_POWER_MASK		0x7

#define PPU_IRQ_MASK_REG		0x2C
#define PSW_OFF_DLY_REG			0x30

#define to_gpu_pd(gpd) container_of(gpd, struct gpu_pm_domain, genpd)

/*
 * gpu specific wrapper around the generic power domain
 */
struct gpu_pm_domain {
	struct regmap *regmap;
	char const *name;
	struct clk *clk;
	int irq;
	struct generic_pm_domain genpd;
};

static spinlock_t ppu_lock;

static inline void gpu_rstn(struct gpu_pm_domain *pd, bool on)
{
	udelay(1);
	regmap_write(pd->regmap, GPU_RSTN_REG, on ? 1 : 0);
}

static inline void gpu_clk_gate(struct gpu_pm_domain *pd, bool on)
{
	regmap_write(pd->regmap, GPU_CLK_GATE_REG, on ? 1 : 0);
	udelay(1);
}

static inline void gpu_iso_b(struct gpu_pm_domain *pd, bool on)
{
	regmap_update_bits(pd->regmap,
		GPU_POWEROFF_GATE_REG, BIT(1), on ? -1U : 0);
}

static inline void gpu_iso_a(struct gpu_pm_domain *pd, bool on)
{
	regmap_update_bits(pd->regmap,
		GPU_POWEROFF_GATE_REG, BIT(0), on ? -1U : 0);
}

static inline void gpu_pwra_on(struct gpu_pm_domain *pd)
{
	unsigned int i;

	for (i = 0; i < 8; i++) {
		regmap_write(pd->regmap, GPU_PSWON_REG, 1 << i);
		udelay(1);
	}
}

static inline void gpu_pwra_off(struct gpu_pm_domain *pd)
{
	regmap_write(pd->regmap, GPU_PSWOFF_REG, GPU_PDA_OFF);
}

static inline void gpu_pwrb_on(struct gpu_pm_domain *pd)
{
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(23));
	udelay(10);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(18));
	udelay(10);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(16));
	udelay(5);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(19));
	udelay(5);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(20));
	udelay(5);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(21));
	udelay(5);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(22));
	udelay(5);
	regmap_write(pd->regmap, GPU_PSWON_REG, BIT(17));
	udelay(5);
}

static inline void gpu_pwrb_off(struct gpu_pm_domain *pd)
{
	regmap_write(pd->regmap, GPU_PSWOFF_REG, GPU_PDB_OFF);
}

static inline void domain_b_on_flow(struct gpu_pm_domain *pd)
{
	gpu_pwrb_on(pd);
	gpu_iso_b(pd, false);
	regmap_write(pd->regmap, GPU_PD_STAT_REG, GPU_PD_STAT_3D);
}

static inline void domain_b_off_flow(struct gpu_pm_domain *pd)
{
	gpu_iso_b(pd, true);
	gpu_pwrb_off(pd);
	regmap_write(pd->regmap, GPU_PD_STAT_REG, GPU_PD_STAT_HOST);
}

static irqreturn_t ppu_irq_handler(int irq, void *dev_id)
{
	struct gpu_pm_domain *pd = dev_id;
	unsigned int rdata;

	regmap_read(pd->regmap, PPU_STAT_REG, &rdata);


	/* gpu power req */
	if (rdata & GPU_POWER_REQ) {
		spin_lock(&ppu_lock);
		if (((rdata >> 16) & GPU_STAT_POWER_MASK)
			== GPU_STAT_3D_2_HOST)
			domain_b_off_flow(pd);
		else if (((rdata >> 16) & GPU_STAT_POWER_MASK)
			== GPU_STAT_HOST_2_3D)
			domain_b_on_flow(pd);

		/* clear gpu power req pending */
		regmap_write(pd->regmap, PPU_STAT_REG, 0x1);
		/* send complete signal to gpu*/
		regmap_read(pd->regmap, PPU_CFG_REG, &rdata);
		regmap_write(pd->regmap, PPU_CFG_REG,
			rdata | PPU_POWER_ON_COMPLETE);
		spin_unlock(&ppu_lock);
	}

	return IRQ_HANDLED;
}

static int gpu_pd_power_on(struct generic_pm_domain *domain)
{
	struct gpu_pm_domain *pd = to_gpu_pd(domain);
	unsigned int rdata;

	regmap_read(pd->regmap, GPU_PD_STAT_REG, &rdata);
	WARN_ON((rdata & GPU_PD_STAT_MASK) != GPU_PD_STAT_ALLOFF);

	spin_lock(&ppu_lock);

	gpu_pwra_on(pd);
	gpu_clk_gate(pd, true);
	gpu_iso_a(pd, false);
	gpu_pwrb_on(pd);
	gpu_iso_b(pd, false);
	gpu_rstn(pd, true);
	udelay(10);
	regmap_write(pd->regmap, GPU_PD_STAT_REG, GPU_PD_STAT_3D);
	regmap_write(pd->regmap, PPU_STAT_REG, 0x1);
	regmap_write(pd->regmap, PPU_IRQ_MASK_REG, 0x1);

	spin_unlock(&ppu_lock);

	return 0;
}

static int gpu_pd_power_off(struct generic_pm_domain *domain)
{
	struct gpu_pm_domain *pd = to_gpu_pd(domain);
	unsigned int rdata;

	regmap_read(pd->regmap, GPU_PD_STAT_REG, &rdata);
	WARN_ON((rdata & GPU_PD_STAT_MASK) == GPU_PD_STAT_ALLOFF);

	spin_lock(&ppu_lock);

	gpu_iso_b(pd, true);
	gpu_iso_a(pd, true);
	gpu_clk_gate(pd, false);
	gpu_rstn(pd, false);
	gpu_pwrb_off(pd);
	gpu_pwra_off(pd);
	regmap_write(pd->regmap, GPU_PD_STAT_REG, GPU_PD_STAT_ALLOFF);
	regmap_write(pd->regmap, PPU_STAT_REG, 0x1);
	regmap_write(pd->regmap, PPU_IRQ_MASK_REG, 0x0);

	spin_unlock(&ppu_lock);

	return 0;
}

static inline int sunxi_get_ic_version(char *version)
{
#define SYS_CFG_BASE 0x03000000
#define VER_REG_OFFS 0x00000024
	void __iomem *io = NULL;
	static char ver = 0xff;
	/* IC version:
	 * A/B/C: 0
	 *     D: 3
	 *     E: 4
	 *     F: 5
	 *        6/7/1/2 to be used in future.
	 */
	*version = 0;
	if (ver == 0xff) {
		io = ioremap(SYS_CFG_BASE, 0x100);
		if (io == NULL) {
			pr_err("%s: ioremap of sys_cfg register failed!\n",
				__func__);
			return -1;
		}
		*version = (char)(readl(io + VER_REG_OFFS) & 0x7);
		iounmap(io);
		ver = *version;
	} else {
		*version = ver;
	}
	return 0;
}

static bool sunxi_ic_version_ctrl(void)
{
	char ic_version = 0;
	sunxi_get_ic_version(&ic_version);
	/*
	 * The flow of jtag reset before gpu reset will cause MIPS crash, so we
	 * will put the domainA, domainB and gpu reset operations to boot0
	 * stage. And in kernel stage, we will always keep domainA poweron.
	 */
	if (ic_version == 0 || ic_version == 3 || ic_version == 4 ||
		ic_version == 5)
		return false;
	return true;
}

static const struct of_device_id gpu_pm_domain_of_match[] __initconst = {
	{
		.compatible = "allwinner,gpu-pd",
	},
	{ },
};

static __init int gpu_pm_init_power_domain(void)
{
	struct device_node *np;
	struct gpu_pm_domain *pd;
	int ret = 0;

	np = of_find_matching_node(NULL, gpu_pm_domain_of_match);
	if (!np) {
		pr_err("%s: failed to gpu power domain\n", __func__);
		ret = -ENODEV;
		goto err_match;
	}

	pd = kzalloc(sizeof(*pd), GFP_KERNEL);
	if (!pd) {
		ret = -ENOMEM;
		goto err_alloc;
	}

	pd->genpd.name = kstrdup_const(strrchr(np->full_name, '/') + 1,
					GFP_KERNEL);
	if (!pd->genpd.name) {
		ret = -ENOMEM;
		goto err_name;
	}

	pd->name = pd->genpd.name;
	pd->regmap = syscon_node_to_regmap(np);
	if (IS_ERR(pd->regmap)) {
		pr_err("%s: no regmap available\n", __func__);
		ret = -EINVAL;
		goto err_regmap;
	}

	/*
	 * Gpu driver will not set and unset ppu runtime counter, it
	 * can make sure the poweron and poweroff function of ppu
	 * must not be called by kernel stage.
	 * Besides the ppu driver will only recept event to control domain B
	 * power status in kernel stage.
	 */
	if (sunxi_ic_version_ctrl()) {
		pd->genpd.power_off = gpu_pd_power_off;
		pd->genpd.power_on = gpu_pd_power_on;
	}
	pd->genpd.flags = GENPD_FLAG_PM_CLK;
	pd->irq = of_irq_get(np, 0);
	if (pd->irq == -EPROBE_DEFER) {
		pr_err("%s:failed to find IRQ number\n", __func__);
		ret = -EPROBE_DEFER;
		goto err_regmap;
	}

	ret = request_irq(pd->irq, ppu_irq_handler,
				0, "ppu_interrupt", (void *)pd);
	if (ret) {
		pr_err("%s:failed to request nIRQ:%d\n", __func__, pd->irq);
		ret = -ENOMEM;
		goto err_regmap;
	}

	pd->clk = of_clk_get_by_name(np, "ppu");
	if (IS_ERR(pd->clk)) {
		pr_err("%s:Unable to find clock\n", __func__);
		pd->clk = NULL;
		ret = -ENOMEM;
		goto err_irq;
	}

	clk_prepare_enable(pd->clk);
	spin_lock_init(&ppu_lock);

	regmap_write(pd->regmap, PPU_CFG_REG, POWER_CTRL_MODE_SW);
	regmap_write(pd->regmap, PPU_IRQ_MASK_REG, 0x1);

	pm_genpd_init(&pd->genpd, NULL, true);
	of_genpd_add_provider_simple(np, &pd->genpd);

	return 0;

err_irq:
	free_irq(pd->irq, pd);
err_regmap:
	kfree_const(pd->genpd.name);
err_name:
	kfree(pd);
err_alloc:
	of_node_put(np);
err_match:
	pr_err("%s: failed to init ppu\n", __func__);
	return ret;
}
core_initcall(gpu_pm_init_power_domain);