/*
 * Xilinx 'Clocking Wizard' driver
 *
 *  Copyright (C) 2013 - 2014 Xilinx
 *
 *  Sören Brinkmann <soren.brinkmann@xilinx.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License v2 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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/module.h>
#include <linux/err.h>

#define WZRD_NUM_OUTPUTS	7
#define WZRD_ACLK_MAX_FREQ	250000000UL

#define WZRD_CLK_CFG_REG(n)	(0x200 + 4 * (n))

#define WZRD_CLKOUT0_FRAC_EN	BIT(18)
#define WZRD_CLKFBOUT_FRAC_EN	BIT(26)

#define WZRD_CLKFBOUT_MULT_SHIFT	8
#define WZRD_CLKFBOUT_MULT_MASK		(0xff << WZRD_CLKFBOUT_MULT_SHIFT)
#define WZRD_DIVCLK_DIVIDE_SHIFT	0
#define WZRD_DIVCLK_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)
#define WZRD_CLKOUT_DIVIDE_SHIFT	0
#define WZRD_CLKOUT_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)

enum clk_wzrd_int_clks {
	wzrd_clk_mul,
	wzrd_clk_mul_div,
	wzrd_clk_int_max
};

/**
 * struct clk_wzrd:
 * @clk_data:		Clock data
 * @nb:			Notifier block
 * @base:		Memory base
 * @clk_in1:		Handle to input clock 'clk_in1'
 * @axi_clk:		Handle to input clock 's_axi_aclk'
 * @clks_internal:	Internal clocks
 * @clkout:		Output clocks
 * @speed_grade:	Speed grade of the device
 * @suspended:		Flag indicating power state of the device
 */
struct clk_wzrd {
	struct clk_onecell_data clk_data;
	struct notifier_block nb;
	void __iomem *base;
	struct clk *clk_in1;
	struct clk *axi_clk;
	struct clk *clks_internal[wzrd_clk_int_max];
	struct clk *clkout[WZRD_NUM_OUTPUTS];
	unsigned int speed_grade;
	bool suspended;
};

#define to_clk_wzrd(_nb) container_of(_nb, struct clk_wzrd, nb)

/* maximum frequencies for input/output clocks per speed grade */
static const unsigned long clk_wzrd_max_freq[] = {
	800000000UL,
	933000000UL,
	1066000000UL
};

static int clk_wzrd_clk_notifier(struct notifier_block *nb, unsigned long event,
				 void *data)
{
	unsigned long max;
	struct clk_notifier_data *ndata = data;
	struct clk_wzrd *clk_wzrd = to_clk_wzrd(nb);

	if (clk_wzrd->suspended)
		return NOTIFY_OK;

	if (ndata->clk == clk_wzrd->clk_in1)
		max = clk_wzrd_max_freq[clk_wzrd->speed_grade - 1];
	else if (ndata->clk == clk_wzrd->axi_clk)
		max = WZRD_ACLK_MAX_FREQ;
	else
		return NOTIFY_DONE;	/* should never happen */

	switch (event) {
	case PRE_RATE_CHANGE:
		if (ndata->new_rate > max)
			return NOTIFY_BAD;
		return NOTIFY_OK;
	case POST_RATE_CHANGE:
	case ABORT_RATE_CHANGE:
	default:
		return NOTIFY_DONE;
	}
}

static int __maybe_unused clk_wzrd_suspend(struct device *dev)
{
	struct clk_wzrd *clk_wzrd = dev_get_drvdata(dev);

	clk_disable_unprepare(clk_wzrd->axi_clk);
	clk_wzrd->suspended = true;

	return 0;
}

static int __maybe_unused clk_wzrd_resume(struct device *dev)
{
	int ret;
	struct clk_wzrd *clk_wzrd = dev_get_drvdata(dev);

	ret = clk_prepare_enable(clk_wzrd->axi_clk);
	if (ret) {
		dev_err(dev, "unable to enable s_axi_aclk\n");
		return ret;
	}

	clk_wzrd->suspended = false;

	return 0;
}

static SIMPLE_DEV_PM_OPS(clk_wzrd_dev_pm_ops, clk_wzrd_suspend,
			 clk_wzrd_resume);

static int clk_wzrd_probe(struct platform_device *pdev)
{
	int i, ret;
	u32 reg;
	unsigned long rate;
	const char *clk_name;
	struct clk_wzrd *clk_wzrd;
	struct resource *mem;
	struct device_node *np = pdev->dev.of_node;

	clk_wzrd = devm_kzalloc(&pdev->dev, sizeof(*clk_wzrd), GFP_KERNEL);
	if (!clk_wzrd)
		return -ENOMEM;
	platform_set_drvdata(pdev, clk_wzrd);

	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	clk_wzrd->base = devm_ioremap_resource(&pdev->dev, mem);
	if (IS_ERR(clk_wzrd->base))
		return PTR_ERR(clk_wzrd->base);

	ret = of_property_read_u32(np, "speed-grade", &clk_wzrd->speed_grade);
	if (!ret) {
		if (clk_wzrd->speed_grade < 1 || clk_wzrd->speed_grade > 3) {
			dev_warn(&pdev->dev, "invalid speed grade '%d'\n",
				 clk_wzrd->speed_grade);
			clk_wzrd->speed_grade = 0;
		}
	}

	clk_wzrd->clk_in1 = devm_clk_get(&pdev->dev, "clk_in1");
	if (IS_ERR(clk_wzrd->clk_in1)) {
		if (clk_wzrd->clk_in1 != ERR_PTR(-EPROBE_DEFER))
			dev_err(&pdev->dev, "clk_in1 not found\n");
		return PTR_ERR(clk_wzrd->clk_in1);
	}

	clk_wzrd->axi_clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
	if (IS_ERR(clk_wzrd->axi_clk)) {
		if (clk_wzrd->axi_clk != ERR_PTR(-EPROBE_DEFER))
			dev_err(&pdev->dev, "s_axi_aclk not found\n");
		return PTR_ERR(clk_wzrd->axi_clk);
	}
	ret = clk_prepare_enable(clk_wzrd->axi_clk);
	if (ret) {
		dev_err(&pdev->dev, "enabling s_axi_aclk failed\n");
		return ret;
	}
	rate = clk_get_rate(clk_wzrd->axi_clk);
	if (rate > WZRD_ACLK_MAX_FREQ) {
		dev_err(&pdev->dev, "s_axi_aclk frequency (%lu) too high\n",
			rate);
		ret = -EINVAL;
		goto err_disable_clk;
	}

	/* we don't support fractional div/mul yet */
	reg = readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
		    WZRD_CLKFBOUT_FRAC_EN;
	reg |= readl(clk_wzrd->base + WZRD_CLK_CFG_REG(2)) &
		     WZRD_CLKOUT0_FRAC_EN;
	if (reg)
		dev_warn(&pdev->dev, "fractional div/mul not supported\n");

	/* register multiplier */
	reg = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
		     WZRD_CLKFBOUT_MULT_MASK) >> WZRD_CLKFBOUT_MULT_SHIFT;
	clk_name = kasprintf(GFP_KERNEL, "%s_mul", dev_name(&pdev->dev));
	if (!clk_name) {
		ret = -ENOMEM;
		goto err_disable_clk;
	}
	clk_wzrd->clks_internal[wzrd_clk_mul] = clk_register_fixed_factor(
			&pdev->dev, clk_name,
			__clk_get_name(clk_wzrd->clk_in1),
			0, reg, 1);
	kfree(clk_name);
	if (IS_ERR(clk_wzrd->clks_internal[wzrd_clk_mul])) {
		dev_err(&pdev->dev, "unable to register fixed-factor clock\n");
		ret = PTR_ERR(clk_wzrd->clks_internal[wzrd_clk_mul]);
		goto err_disable_clk;
	}

	/* register div */
	reg = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
			WZRD_DIVCLK_DIVIDE_MASK) >> WZRD_DIVCLK_DIVIDE_SHIFT;
	clk_name = kasprintf(GFP_KERNEL, "%s_mul_div", dev_name(&pdev->dev));
	if (!clk_name) {
		ret = -ENOMEM;
		goto err_rm_int_clk;
	}

	clk_wzrd->clks_internal[wzrd_clk_mul_div] = clk_register_fixed_factor(
			&pdev->dev, clk_name,
			__clk_get_name(clk_wzrd->clks_internal[wzrd_clk_mul]),
			0, 1, reg);
	if (IS_ERR(clk_wzrd->clks_internal[wzrd_clk_mul_div])) {
		dev_err(&pdev->dev, "unable to register divider clock\n");
		ret = PTR_ERR(clk_wzrd->clks_internal[wzrd_clk_mul_div]);
		goto err_rm_int_clk;
	}

	/* register div per output */
	for (i = WZRD_NUM_OUTPUTS - 1; i >= 0 ; i--) {
		const char *clkout_name;

		if (of_property_read_string_index(np, "clock-output-names", i,
						  &clkout_name)) {
			dev_err(&pdev->dev,
				"clock output name not specified\n");
			ret = -EINVAL;
			goto err_rm_int_clks;
		}
		reg = readl(clk_wzrd->base + WZRD_CLK_CFG_REG(2) + i * 12);
		reg &= WZRD_CLKOUT_DIVIDE_MASK;
		reg >>= WZRD_CLKOUT_DIVIDE_SHIFT;
		clk_wzrd->clkout[i] = clk_register_fixed_factor(&pdev->dev,
				clkout_name, clk_name, 0, 1, reg);
		if (IS_ERR(clk_wzrd->clkout[i])) {
			int j;

			for (j = i + 1; j < WZRD_NUM_OUTPUTS; j++)
				clk_unregister(clk_wzrd->clkout[j]);
			dev_err(&pdev->dev,
				"unable to register divider clock\n");
			ret = PTR_ERR(clk_wzrd->clkout[i]);
			goto err_rm_int_clks;
		}
	}

	kfree(clk_name);

	clk_wzrd->clk_data.clks = clk_wzrd->clkout;
	clk_wzrd->clk_data.clk_num = ARRAY_SIZE(clk_wzrd->clkout);
	of_clk_add_provider(np, of_clk_src_onecell_get, &clk_wzrd->clk_data);

	if (clk_wzrd->speed_grade) {
		clk_wzrd->nb.notifier_call = clk_wzrd_clk_notifier;

		ret = clk_notifier_register(clk_wzrd->clk_in1,
					    &clk_wzrd->nb);
		if (ret)
			dev_warn(&pdev->dev,
				 "unable to register clock notifier\n");

		ret = clk_notifier_register(clk_wzrd->axi_clk, &clk_wzrd->nb);
		if (ret)
			dev_warn(&pdev->dev,
				 "unable to register clock notifier\n");
	}

	return 0;

err_rm_int_clks:
	clk_unregister(clk_wzrd->clks_internal[1]);
err_rm_int_clk:
	kfree(clk_name);
	clk_unregister(clk_wzrd->clks_internal[0]);
err_disable_clk:
	clk_disable_unprepare(clk_wzrd->axi_clk);

	return ret;
}

static int clk_wzrd_remove(struct platform_device *pdev)
{
	int i;
	struct clk_wzrd *clk_wzrd = platform_get_drvdata(pdev);

	of_clk_del_provider(pdev->dev.of_node);

	for (i = 0; i < WZRD_NUM_OUTPUTS; i++)
		clk_unregister(clk_wzrd->clkout[i]);
	for (i = 0; i < wzrd_clk_int_max; i++)
		clk_unregister(clk_wzrd->clks_internal[i]);

	if (clk_wzrd->speed_grade) {
		clk_notifier_unregister(clk_wzrd->axi_clk, &clk_wzrd->nb);
		clk_notifier_unregister(clk_wzrd->clk_in1, &clk_wzrd->nb);
	}

	clk_disable_unprepare(clk_wzrd->axi_clk);

	return 0;
}

static const struct of_device_id clk_wzrd_ids[] = {
	{ .compatible = "xlnx,clocking-wizard" },
	{ },
};
MODULE_DEVICE_TABLE(of, clk_wzrd_ids);

static struct platform_driver clk_wzrd_driver = {
	.driver = {
		.name = "clk-wizard",
		.of_match_table = clk_wzrd_ids,
		.pm = &clk_wzrd_dev_pm_ops,
	},
	.probe = clk_wzrd_probe,
	.remove = clk_wzrd_remove,
};
module_platform_driver(clk_wzrd_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com");
MODULE_DESCRIPTION("Driver for the Xilinx Clocking Wizard IP core");