/*
 * Atmel SDMMC controller driver.
 *
 * Copyright (C) 2015 Atmel,
 *		 2015 Ludovic Desroches <ludovic.desroches@atmel.com>
 *
 * This software is licensed under the terms of the GNU General Public
 * License version 2, as published by the Free Software Foundation, and
 * may be copied, distributed, and modified under those terms.
 *
 * 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/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/mmc/host.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>

#include "sdhci-pltfm.h"

#define SDMMC_CACR	0x230
#define		SDMMC_CACR_CAPWREN	BIT(0)
#define		SDMMC_CACR_KEY		(0x46 << 8)

struct sdhci_at91_priv {
	struct clk *hclock;
	struct clk *gck;
	struct clk *mainck;
};

static const struct sdhci_ops sdhci_at91_sama5d2_ops = {
	.set_clock		= sdhci_set_clock,
	.set_bus_width		= sdhci_set_bus_width,
	.reset			= sdhci_reset,
	.set_uhs_signaling	= sdhci_set_uhs_signaling,
};

static const struct sdhci_pltfm_data soc_data_sama5d2 = {
	.ops = &sdhci_at91_sama5d2_ops,
};

static const struct of_device_id sdhci_at91_dt_match[] = {
	{ .compatible = "atmel,sama5d2-sdhci", .data = &soc_data_sama5d2 },
	{}
};

static int sdhci_at91_probe(struct platform_device *pdev)
{
	const struct of_device_id	*match;
	const struct sdhci_pltfm_data	*soc_data;
	struct sdhci_host		*host;
	struct sdhci_pltfm_host		*pltfm_host;
	struct sdhci_at91_priv		*priv;
	unsigned int			caps0, caps1;
	unsigned int			clk_base, clk_mul;
	unsigned int			gck_rate, real_gck_rate;
	int				ret;

	match = of_match_device(sdhci_at91_dt_match, &pdev->dev);
	if (!match)
		return -EINVAL;
	soc_data = match->data;

	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		dev_err(&pdev->dev, "unable to allocate private data\n");
		return -ENOMEM;
	}

	priv->mainck = devm_clk_get(&pdev->dev, "baseclk");
	if (IS_ERR(priv->mainck)) {
		dev_err(&pdev->dev, "failed to get baseclk\n");
		return PTR_ERR(priv->mainck);
	}

	priv->hclock = devm_clk_get(&pdev->dev, "hclock");
	if (IS_ERR(priv->hclock)) {
		dev_err(&pdev->dev, "failed to get hclock\n");
		return PTR_ERR(priv->hclock);
	}

	priv->gck = devm_clk_get(&pdev->dev, "multclk");
	if (IS_ERR(priv->gck)) {
		dev_err(&pdev->dev, "failed to get multclk\n");
		return PTR_ERR(priv->gck);
	}

	host = sdhci_pltfm_init(pdev, soc_data, 0);
	if (IS_ERR(host))
		return PTR_ERR(host);

	/*
	 * The mult clock is provided by as a generated clock by the PMC
	 * controller. In order to set the rate of gck, we have to get the
	 * base clock rate and the clock mult from capabilities.
	 */
	clk_prepare_enable(priv->hclock);
	caps0 = readl(host->ioaddr + SDHCI_CAPABILITIES);
	caps1 = readl(host->ioaddr + SDHCI_CAPABILITIES_1);
	clk_base = (caps0 & SDHCI_CLOCK_V3_BASE_MASK) >> SDHCI_CLOCK_BASE_SHIFT;
	clk_mul = (caps1 & SDHCI_CLOCK_MUL_MASK) >> SDHCI_CLOCK_MUL_SHIFT;
	gck_rate = clk_base * 1000000 * (clk_mul + 1);
	ret = clk_set_rate(priv->gck, gck_rate);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to set gck");
		goto hclock_disable_unprepare;
		return -EINVAL;
	}
	/*
	 * We need to check if we have the requested rate for gck because in
	 * some cases this rate could be not supported. If it happens, the rate
	 * is the closest one gck can provide. We have to update the value
	 * of clk mul.
	 */
	real_gck_rate = clk_get_rate(priv->gck);
	if (real_gck_rate != gck_rate) {
		clk_mul = real_gck_rate / (clk_base * 1000000) - 1;
		caps1 &= (~SDHCI_CLOCK_MUL_MASK);
		caps1 |= ((clk_mul << SDHCI_CLOCK_MUL_SHIFT) & SDHCI_CLOCK_MUL_MASK);
		/* Set capabilities in r/w mode. */
		writel(SDMMC_CACR_KEY | SDMMC_CACR_CAPWREN, host->ioaddr + SDMMC_CACR);
		writel(caps1, host->ioaddr + SDHCI_CAPABILITIES_1);
		/* Set capabilities in ro mode. */
		writel(0, host->ioaddr + SDMMC_CACR);
		dev_info(&pdev->dev, "update clk mul to %u as gck rate is %u Hz\n",
			 clk_mul, real_gck_rate);
	}

	clk_prepare_enable(priv->mainck);
	clk_prepare_enable(priv->gck);

	pltfm_host = sdhci_priv(host);
	pltfm_host->priv = priv;

	ret = mmc_of_parse(host->mmc);
	if (ret)
		goto clocks_disable_unprepare;

	sdhci_get_of_property(pdev);

	ret = sdhci_add_host(host);
	if (ret)
		goto clocks_disable_unprepare;

	return 0;

clocks_disable_unprepare:
	clk_disable_unprepare(priv->gck);
	clk_disable_unprepare(priv->mainck);
hclock_disable_unprepare:
	clk_disable_unprepare(priv->hclock);
	sdhci_pltfm_free(pdev);
	return ret;
}

static int sdhci_at91_remove(struct platform_device *pdev)
{
	struct sdhci_host	*host = platform_get_drvdata(pdev);
	struct sdhci_pltfm_host	*pltfm_host = sdhci_priv(host);
	struct sdhci_at91_priv	*priv = pltfm_host->priv;

	sdhci_pltfm_unregister(pdev);

	clk_disable_unprepare(priv->gck);
	clk_disable_unprepare(priv->hclock);
	clk_disable_unprepare(priv->mainck);

	return 0;
}

static struct platform_driver sdhci_at91_driver = {
	.driver		= {
		.name	= "sdhci-at91",
		.owner	= THIS_MODULE,
		.of_match_table = sdhci_at91_dt_match,
		.pm	= SDHCI_PLTFM_PMOPS,
	},
	.probe		= sdhci_at91_probe,
	.remove		= sdhci_at91_remove,
};

module_platform_driver(sdhci_at91_driver);

MODULE_DESCRIPTION("SDHCI driver for at91");
MODULE_AUTHOR("Ludovic Desroches <ludovic.desroches@atmel.com>");
MODULE_LICENSE("GPL v2");