/*
   * AXI clkgen driver
   *
   * Copyright 2012-2013 Analog Devices Inc.
   *  Author: Lars-Peter Clausen <lars@metafoo.de>
   *
   * Licensed under the GPL-2.
   *
   */
  
  #include <linux/platform_device.h>
  #include <linux/clk-provider.h>
  #include <linux/clk.h>
  #include <linux/slab.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/module.h>
  #include <linux/err.h>
  
  #define AXI_CLKGEN_REG_UPDATE_ENABLE	0x04
  #define AXI_CLKGEN_REG_CLK_OUT1		0x08
  #define AXI_CLKGEN_REG_CLK_OUT2		0x0c
  #define AXI_CLKGEN_REG_CLK_DIV		0x10
  #define AXI_CLKGEN_REG_CLK_FB1		0x14
  #define AXI_CLKGEN_REG_CLK_FB2		0x18
  #define AXI_CLKGEN_REG_LOCK1		0x1c
  #define AXI_CLKGEN_REG_LOCK2		0x20
  #define AXI_CLKGEN_REG_LOCK3		0x24
  #define AXI_CLKGEN_REG_FILTER1		0x28
  #define AXI_CLKGEN_REG_FILTER2		0x2c
  
  struct axi_clkgen {
  	void __iomem *base;
  	struct clk_hw clk_hw;
  };
  
  static uint32_t axi_clkgen_lookup_filter(unsigned int m)
  {
  	switch (m) {
  	case 0:
  		return 0x01001990;
  	case 1:
  		return 0x01001190;
  	case 2:
  		return 0x01009890;
  	case 3:
  		return 0x01001890;
  	case 4:
  		return 0x01008890;
  	case 5 ... 8:
  		return 0x01009090;
  	case 9 ... 11:
  		return 0x01000890;
  	case 12:
  		return 0x08009090;
  	case 13 ... 22:
  		return 0x01001090;
  	case 23 ... 36:
  		return 0x01008090;
  	case 37 ... 46:
  		return 0x08001090;
  	default:
  		return 0x08008090;
  	}
  }
  
  static const uint32_t axi_clkgen_lock_table[] = {
  	0x060603e8, 0x060603e8, 0x080803e8, 0x0b0b03e8,
  	0x0e0e03e8, 0x111103e8, 0x131303e8, 0x161603e8,
  	0x191903e8, 0x1c1c03e8, 0x1f1f0384, 0x1f1f0339,
  	0x1f1f02ee, 0x1f1f02bc, 0x1f1f028a, 0x1f1f0271,
  	0x1f1f023f, 0x1f1f0226, 0x1f1f020d, 0x1f1f01f4,
  	0x1f1f01db, 0x1f1f01c2, 0x1f1f01a9, 0x1f1f0190,
  	0x1f1f0190, 0x1f1f0177, 0x1f1f015e, 0x1f1f015e,
  	0x1f1f0145, 0x1f1f0145, 0x1f1f012c, 0x1f1f012c,
  	0x1f1f012c, 0x1f1f0113, 0x1f1f0113, 0x1f1f0113,
  };
  
  static uint32_t axi_clkgen_lookup_lock(unsigned int m)
  {
  	if (m < ARRAY_SIZE(axi_clkgen_lock_table))
  		return axi_clkgen_lock_table[m];
  	return 0x1f1f00fa;
  }
  
  static const unsigned int fpfd_min = 10000;
  static const unsigned int fpfd_max = 300000;
  static const unsigned int fvco_min = 600000;
  static const unsigned int fvco_max = 1200000;
  
  static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout,
  	unsigned int *best_d, unsigned int *best_m, unsigned int *best_dout)
  {
  	unsigned long d, d_min, d_max, _d_min, _d_max;
  	unsigned long m, m_min, m_max;
  	unsigned long f, dout, best_f, fvco;
  
  	fin /= 1000;
  	fout /= 1000;
  
  	best_f = ULONG_MAX;
  	*best_d = 0;
  	*best_m = 0;
  	*best_dout = 0;
  
  	d_min = max_t(unsigned long, DIV_ROUND_UP(fin, fpfd_max), 1);
  	d_max = min_t(unsigned long, fin / fpfd_min, 80);
  
  	m_min = max_t(unsigned long, DIV_ROUND_UP(fvco_min, fin) * d_min, 1);
  	m_max = min_t(unsigned long, fvco_max * d_max / fin, 64);
  
  	for (m = m_min; m <= m_max; m++) {
  		_d_min = max(d_min, DIV_ROUND_UP(fin * m, fvco_max));
  		_d_max = min(d_max, fin * m / fvco_min);
  
  		for (d = _d_min; d <= _d_max; d++) {
  			fvco = fin * m / d;
  
  			dout = DIV_ROUND_CLOSEST(fvco, fout);
  			dout = clamp_t(unsigned long, dout, 1, 128);
  			f = fvco / dout;
  			if (abs(f - fout) < abs(best_f - fout)) {
  				best_f = f;
  				*best_d = d;
  				*best_m = m;
  				*best_dout = dout;
  				if (best_f == fout)
  					return;
  			}
  		}
  	}
  }
  
  static void axi_clkgen_calc_clk_params(unsigned int divider, unsigned int *low,
  	unsigned int *high, unsigned int *edge, unsigned int *nocount)
  {
  	if (divider == 1)
  		*nocount = 1;
  	else
  		*nocount = 0;
  
  	*high = divider / 2;
  	*edge = divider % 2;
  	*low = divider - *high;
  }
  
  static void axi_clkgen_write(struct axi_clkgen *axi_clkgen,
  	unsigned int reg, unsigned int val)
  {
  	writel(val, axi_clkgen->base + reg);
  }
  
  static void axi_clkgen_read(struct axi_clkgen *axi_clkgen,
  	unsigned int reg, unsigned int *val)
  {
  	*val = readl(axi_clkgen->base + reg);
  }
  
  static struct axi_clkgen *clk_hw_to_axi_clkgen(struct clk_hw *clk_hw)
  {
  	return container_of(clk_hw, struct axi_clkgen, clk_hw);
  }
  
  static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
  	unsigned long rate, unsigned long parent_rate)
  {
  	struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
  	unsigned int d, m, dout;
  	unsigned int nocount;
  	unsigned int high;
  	unsigned int edge;
  	unsigned int low;
  	uint32_t filter;
  	uint32_t lock;
  
  	if (parent_rate == 0 || rate == 0)
  		return -EINVAL;
  
  	axi_clkgen_calc_params(parent_rate, rate, &d, &m, &dout);
  
  	if (d == 0 || dout == 0 || m == 0)
  		return -EINVAL;
  
  	filter = axi_clkgen_lookup_filter(m - 1);
  	lock = axi_clkgen_lookup_lock(m - 1);
  
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_UPDATE_ENABLE, 0);
  
  	axi_clkgen_calc_clk_params(dout, &low, &high, &edge, &nocount);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT1,
  		(high << 6) | low);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT2,
  		(edge << 7) | (nocount << 6));
  
  	axi_clkgen_calc_clk_params(d, &low, &high, &edge, &nocount);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_DIV,
  		(edge << 13) | (nocount << 12) | (high << 6) | low);
  
  	axi_clkgen_calc_clk_params(m, &low, &high, &edge, &nocount);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_FB1,
  		(high << 6) | low);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_FB2,
  		(edge << 7) | (nocount << 6));
  
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK1, lock & 0x3ff);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK2,
  		(((lock >> 16) & 0x1f) << 10) | 0x1);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK3,
  		(((lock >> 24) & 0x1f) << 10) | 0x3e9);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_FILTER1, filter >> 16);
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_FILTER2, filter);
  
  	axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_UPDATE_ENABLE, 1);
  
  	return 0;
  }
  
  static long axi_clkgen_round_rate(struct clk_hw *hw, unsigned long rate,
  	unsigned long *parent_rate)
  {
  	unsigned int d, m, dout;
  
  	axi_clkgen_calc_params(*parent_rate, rate, &d, &m, &dout);
  
  	if (d == 0 || dout == 0 || m == 0)
  		return -EINVAL;
  
  	return *parent_rate / d * m / dout;
  }
  
  static unsigned long axi_clkgen_recalc_rate(struct clk_hw *clk_hw,
  	unsigned long parent_rate)
  {
  	struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
  	unsigned int d, m, dout;
  	unsigned int reg;
  	unsigned long long tmp;
  
  	axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT1, &reg);
  	dout = (reg & 0x3f) + ((reg >> 6) & 0x3f);
  	axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_DIV, &reg);
  	d = (reg & 0x3f) + ((reg >> 6) & 0x3f);
  	axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_FB1, &reg);
  	m = (reg & 0x3f) + ((reg >> 6) & 0x3f);
  
  	if (d == 0 || dout == 0)
  		return 0;
  
  	tmp = (unsigned long long)(parent_rate / d) * m;
  	do_div(tmp, dout);
  
  	if (tmp > ULONG_MAX)
  		return ULONG_MAX;
  
  	return tmp;
  }
  
  static const struct clk_ops axi_clkgen_ops = {
  	.recalc_rate = axi_clkgen_recalc_rate,
  	.round_rate = axi_clkgen_round_rate,
  	.set_rate = axi_clkgen_set_rate,
  };
  
  static int axi_clkgen_probe(struct platform_device *pdev)
  {
  	struct axi_clkgen *axi_clkgen;
  	struct clk_init_data init;
  	const char *parent_name;
  	const char *clk_name;
  	struct resource *mem;
  	struct clk *clk;
  
  	axi_clkgen = devm_kzalloc(&pdev->dev, sizeof(*axi_clkgen), GFP_KERNEL);
  	if (!axi_clkgen)
  		return -ENOMEM;
  
  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	axi_clkgen->base = devm_ioremap_resource(&pdev->dev, mem);
  	if (IS_ERR(axi_clkgen->base))
  		return PTR_ERR(axi_clkgen->base);
  
  	parent_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
  	if (!parent_name)
  		return -EINVAL;
  
  	clk_name = pdev->dev.of_node->name;
  	of_property_read_string(pdev->dev.of_node, "clock-output-names",
  		&clk_name);
  
  	init.name = clk_name;
  	init.ops = &axi_clkgen_ops;
  	init.flags = 0;
  	init.parent_names = &parent_name;
  	init.num_parents = 1;
  
  	axi_clkgen->clk_hw.init = &init;
  	clk = devm_clk_register(&pdev->dev, &axi_clkgen->clk_hw);
  	if (IS_ERR(clk))
  		return PTR_ERR(clk);
  
  	return of_clk_add_provider(pdev->dev.of_node, of_clk_src_simple_get,
  				    clk);
  }
  
  static int axi_clkgen_remove(struct platform_device *pdev)
  {
  	of_clk_del_provider(pdev->dev.of_node);
  
  	return 0;
  }
  
  static const struct of_device_id axi_clkgen_ids[] = {
  	{ .compatible = "adi,axi-clkgen-1.00.a" },
  	{ },
  };
  MODULE_DEVICE_TABLE(of, axi_clkgen_ids);
  
  static struct platform_driver axi_clkgen_driver = {
  	.driver = {
  		.name = "adi-axi-clkgen",
  		.owner = THIS_MODULE,
  		.of_match_table = axi_clkgen_ids,
  	},
  	.probe = axi_clkgen_probe,
  	.remove = axi_clkgen_remove,
  };
  module_platform_driver(axi_clkgen_driver);
  
  MODULE_LICENSE("GPL v2");
  MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
  MODULE_DESCRIPTION("Driver for the Analog Devices' AXI clkgen pcore clock generator");