drivers/clk/sunxi/clk-factors.c

   1 /*
   2  * Copyright (C) 2013 Emilio López <emilio@elopez.com.ar>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Adjustable factor-based clock implementation
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/module.h>
  13 #include <linux/slab.h>
  14 #include <linux/io.h>
  15 #include <linux/err.h>
  16 #include <linux/string.h>
  17
  18 #include <linux/delay.h>
  19
  20 #include "clk-factors.h"
  21
  22 /*
  23  * DOC: basic adjustable factor-based clock that cannot gate
  24  *
  25  * Traits of this clock:
  26  * prepare - clk_prepare only ensures that parents are prepared
  27  * enable - clk_enable only ensures that parents are enabled
  28  * rate - rate is adjustable.
  29  *        clk->rate = (parent->rate * N * (K + 1) >> P) / (M + 1)
  30  * parent - fixed parent.  No clk_set_parent support
  31  */
  32
  33 struct clk_factors {
  34         struct clk_hw hw;
  35         void __iomem *reg;
  36         struct clk_factors_config *config;
  37         void (*get_factors) (u32 *rate, u32 parent, u8 *n, u8 *k, u8 *m, u8 *p);
  38         spinlock_t *lock;
  39 };
  40
  41 #define to_clk_factors(_hw) container_of(_hw, struct clk_factors, hw)
  42
  43 #define SETMASK(len, pos)               (((-1U) >> (31-len))  << (pos))
  44 #define CLRMASK(len, pos)               (~(SETMASK(len, pos)))
  45 #define FACTOR_GET(bit, len, reg)       (((reg) & SETMASK(len, bit)) >> (bit))
  46
  47 #define FACTOR_SET(bit, len, reg, val) \
  48         (((reg) & CLRMASK(len, bit)) | (val << (bit)))
  49
  50 static unsigned long clk_factors_recalc_rate(struct clk_hw *hw,
  51                                              unsigned long parent_rate)
  52 {
  53         u8 n = 1, k = 0, p = 0, m = 0;
  54         u32 reg;
  55         unsigned long rate;
  56         struct clk_factors *factors = to_clk_factors(hw);
  57         struct clk_factors_config *config = factors->config;
  58
  59         /* Fetch the register value */
  60         reg = readl(factors->reg);
  61
  62         /* Get each individual factor if applicable */
  63         if (config->nwidth != SUNXI_FACTORS_NOT_APPLICABLE)
  64                 n = FACTOR_GET(config->nshift, config->nwidth, reg);
  65         if (config->kwidth != SUNXI_FACTORS_NOT_APPLICABLE)
  66                 k = FACTOR_GET(config->kshift, config->kwidth, reg);
  67         if (config->mwidth != SUNXI_FACTORS_NOT_APPLICABLE)
  68                 m = FACTOR_GET(config->mshift, config->mwidth, reg);
  69         if (config->pwidth != SUNXI_FACTORS_NOT_APPLICABLE)
  70                 p = FACTOR_GET(config->pshift, config->pwidth, reg);
  71
  72         /* Calculate the rate */
  73         rate = (parent_rate * n * (k + 1) >> p) / (m + 1);
  74
  75         return rate;
  76 }
  77
  78 static long clk_factors_round_rate(struct clk_hw *hw, unsigned long rate,
  79                                    unsigned long *parent_rate)
  80 {
  81         struct clk_factors *factors = to_clk_factors(hw);
  82         factors->get_factors((u32 *)&rate, (u32)*parent_rate,
  83                              NULL, NULL, NULL, NULL);
  84
  85         return rate;
  86 }
  87
  88 static int clk_factors_set_rate(struct clk_hw *hw, unsigned long rate,
  89                                 unsigned long parent_rate)
  90 {
  91         u8 n, k, m, p;
  92         u32 reg;
  93         struct clk_factors *factors = to_clk_factors(hw);
  94         struct clk_factors_config *config = factors->config;
  95         unsigned long flags = 0;
  96
  97         factors->get_factors((u32 *)&rate, (u32)parent_rate, &n, &k, &m, &p);
  98
  99         if (factors->lock)
 100                 spin_lock_irqsave(factors->lock, flags);
 101
 102         /* Fetch the register value */
 103         reg = readl(factors->reg);
 104
 105         /* Set up the new factors - macros do not do anything if width is 0 */
 106         reg = FACTOR_SET(config->nshift, config->nwidth, reg, n);
 107         reg = FACTOR_SET(config->kshift, config->kwidth, reg, k);
 108         reg = FACTOR_SET(config->mshift, config->mwidth, reg, m);
 109         reg = FACTOR_SET(config->pshift, config->pwidth, reg, p);
 110
 111         /* Apply them now */
 112         writel(reg, factors->reg);
 113
 114         /* delay 500us so pll stabilizes */
 115         __delay((rate >> 20) * 500 / 2);
 116
 117         if (factors->lock)
 118                 spin_unlock_irqrestore(factors->lock, flags);
 119
 120         return 0;
 121 }
 122
 123 static const struct clk_ops clk_factors_ops = {
 124         .recalc_rate = clk_factors_recalc_rate,
 125         .round_rate = clk_factors_round_rate,
 126         .set_rate = clk_factors_set_rate,
 127 };
 128
 129 /**
 130  * clk_register_factors - register a factors clock with
 131  * the clock framework
 132  * @dev: device registering this clock
 133  * @name: name of this clock
 134  * @parent_name: name of clock's parent
 135  * @flags: framework-specific flags
 136  * @reg: register address to adjust factors
 137  * @config: shift and width of factors n, k, m and p
 138  * @get_factors: function to calculate the factors for a given frequency
 139  * @lock: shared register lock for this clock
 140  */
 141 struct clk *clk_register_factors(struct device *dev, const char *name,
 142                                  const char *parent_name,
 143                                  unsigned long flags, void __iomem *reg,
 144                                  struct clk_factors_config *config,
 145                                  void (*get_factors)(u32 *rate, u32 parent,
 146                                                      u8 *n, u8 *k, u8 *m, u8 *p),
 147                                  spinlock_t *lock)
 148 {
 149         struct clk_factors *factors;
 150         struct clk *clk;
 151         struct clk_init_data init;
 152
 153         /* allocate the factors */
 154         factors = kzalloc(sizeof(struct clk_factors), GFP_KERNEL);
 155         if (!factors) {
 156                 pr_err("%s: could not allocate factors clk\n", __func__);
 157                 return ERR_PTR(-ENOMEM);
 158         }
 159
 160         init.name = name;
 161         init.ops = &clk_factors_ops;
 162         init.flags = flags;
 163         init.parent_names = (parent_name ? &parent_name : NULL);
 164         init.num_parents = (parent_name ? 1 : 0);
 165
 166         /* struct clk_factors assignments */
 167         factors->reg = reg;
 168         factors->config = config;
 169         factors->lock = lock;
 170         factors->hw.init = &init;
 171         factors->get_factors = get_factors;
 172
 173         /* register the clock */
 174         clk = clk_register(dev, &factors->hw);
 175
 176         if (IS_ERR(clk))
 177                 kfree(factors);
 178
 179         return clk;
 180 }