drivers/clk/sunxi/clk-sun6i-ar100.c

   1 /*
   2  * Copyright (C) 2014 Free Electrons
   3  *
   4  * License Terms: GNU General Public License v2
   5  * Author: Boris BREZILLON <boris.brezillon@free-electrons.com>
   6  *
   7  * Allwinner A31 AR100 clock driver
   8  *
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/module.h>
  13 #include <linux/of.h>
  14 #include <linux/platform_device.h>
  15
  16 #define SUN6I_AR100_MAX_PARENTS         4
  17 #define SUN6I_AR100_SHIFT_MASK          0x3
  18 #define SUN6I_AR100_SHIFT_MAX           SUN6I_AR100_SHIFT_MASK
  19 #define SUN6I_AR100_SHIFT_SHIFT         4
  20 #define SUN6I_AR100_DIV_MASK            0x1f
  21 #define SUN6I_AR100_DIV_MAX             (SUN6I_AR100_DIV_MASK + 1)
  22 #define SUN6I_AR100_DIV_SHIFT           8
  23 #define SUN6I_AR100_MUX_MASK            0x3
  24 #define SUN6I_AR100_MUX_SHIFT           16
  25
  26 struct ar100_clk {
  27         struct clk_hw hw;
  28         void __iomem *reg;
  29 };
  30
  31 static inline struct ar100_clk *to_ar100_clk(struct clk_hw *hw)
  32 {
  33         return container_of(hw, struct ar100_clk, hw);
  34 }
  35
  36 static unsigned long ar100_recalc_rate(struct clk_hw *hw,
  37                                        unsigned long parent_rate)
  38 {
  39         struct ar100_clk *clk = to_ar100_clk(hw);
  40         u32 val = readl(clk->reg);
  41         int shift = (val >> SUN6I_AR100_SHIFT_SHIFT) & SUN6I_AR100_SHIFT_MASK;
  42         int div = (val >> SUN6I_AR100_DIV_SHIFT) & SUN6I_AR100_DIV_MASK;
  43
  44         return (parent_rate >> shift) / (div + 1);
  45 }
  46
  47 static long ar100_determine_rate(struct clk_hw *hw, unsigned long rate,
  48                                  unsigned long *best_parent_rate,
  49                                  struct clk **best_parent_clk)
  50 {
  51         int nparents = __clk_get_num_parents(hw->clk);
  52         long best_rate = -EINVAL;
  53         int i;
  54
  55         *best_parent_clk = NULL;
  56
  57         for (i = 0; i < nparents; i++) {
  58                 unsigned long parent_rate;
  59                 unsigned long tmp_rate;
  60                 struct clk *parent;
  61                 unsigned long div;
  62                 int shift;
  63
  64                 parent = clk_get_parent_by_index(hw->clk, i);
  65                 parent_rate = __clk_get_rate(parent);
  66                 div = DIV_ROUND_UP(parent_rate, rate);
  67
  68                 /*
  69                  * The AR100 clk contains 2 divisors:
  70                  * - one power of 2 divisor
  71                  * - one regular divisor
  72                  *
  73                  * First check if we can safely shift (or divide by a power
  74                  * of 2) without losing precision on the requested rate.
  75                  */
  76                 shift = ffs(div) - 1;
  77                 if (shift > SUN6I_AR100_SHIFT_MAX)
  78                         shift = SUN6I_AR100_SHIFT_MAX;
  79
  80                 div >>= shift;
  81
  82                 /*
  83                  * Then if the divisor is still bigger than what the HW
  84                  * actually supports, use a bigger shift (or power of 2
  85                  * divider) value and accept to lose some precision.
  86                  */
  87                 while (div > SUN6I_AR100_DIV_MAX) {
  88                         shift++;
  89                         div >>= 1;
  90                         if (shift > SUN6I_AR100_SHIFT_MAX)
  91                                 break;
  92                 }
  93
  94                 /*
  95                  * If the shift value (or power of 2 divider) is bigger
  96                  * than what the HW actually support, skip this parent.
  97                  */
  98                 if (shift > SUN6I_AR100_SHIFT_MAX)
  99                         continue;
 100
 101                 tmp_rate = (parent_rate >> shift) / div;
 102                 if (!*best_parent_clk || tmp_rate > best_rate) {
 103                         *best_parent_clk = parent;
 104                         *best_parent_rate = parent_rate;
 105                         best_rate = tmp_rate;
 106                 }
 107         }
 108
 109         return best_rate;
 110 }
 111
 112 static int ar100_set_parent(struct clk_hw *hw, u8 index)
 113 {
 114         struct ar100_clk *clk = to_ar100_clk(hw);
 115         u32 val = readl(clk->reg);
 116
 117         if (index >= SUN6I_AR100_MAX_PARENTS)
 118                 return -EINVAL;
 119
 120         val &= ~(SUN6I_AR100_MUX_MASK << SUN6I_AR100_MUX_SHIFT);
 121         val |= (index << SUN6I_AR100_MUX_SHIFT);
 122         writel(val, clk->reg);
 123
 124         return 0;
 125 }
 126
 127 static u8 ar100_get_parent(struct clk_hw *hw)
 128 {
 129         struct ar100_clk *clk = to_ar100_clk(hw);
 130         return (readl(clk->reg) >> SUN6I_AR100_MUX_SHIFT) &
 131                SUN6I_AR100_MUX_MASK;
 132 }
 133
 134 static int ar100_set_rate(struct clk_hw *hw, unsigned long rate,
 135                           unsigned long parent_rate)
 136 {
 137         unsigned long div = parent_rate / rate;
 138         struct ar100_clk *clk = to_ar100_clk(hw);
 139         u32 val = readl(clk->reg);
 140         int shift;
 141
 142         if (parent_rate % rate)
 143                 return -EINVAL;
 144
 145         shift = ffs(div) - 1;
 146         if (shift > SUN6I_AR100_SHIFT_MAX)
 147                 shift = SUN6I_AR100_SHIFT_MAX;
 148
 149         div >>= shift;
 150
 151         if (div > SUN6I_AR100_DIV_MAX)
 152                 return -EINVAL;
 153
 154         val &= ~((SUN6I_AR100_SHIFT_MASK << SUN6I_AR100_SHIFT_SHIFT) |
 155                  (SUN6I_AR100_DIV_MASK << SUN6I_AR100_DIV_SHIFT));
 156         val |= (shift << SUN6I_AR100_SHIFT_SHIFT) |
 157                (div << SUN6I_AR100_DIV_SHIFT);
 158         writel(val, clk->reg);
 159
 160         return 0;
 161 }
 162
 163 static struct clk_ops ar100_ops = {
 164         .recalc_rate = ar100_recalc_rate,
 165         .determine_rate = ar100_determine_rate,
 166         .set_parent = ar100_set_parent,
 167         .get_parent = ar100_get_parent,
 168         .set_rate = ar100_set_rate,
 169 };
 170
 171 static int sun6i_a31_ar100_clk_probe(struct platform_device *pdev)
 172 {
 173         const char *parents[SUN6I_AR100_MAX_PARENTS];
 174         struct device_node *np = pdev->dev.of_node;
 175         const char *clk_name = np->name;
 176         struct clk_init_data init;
 177         struct ar100_clk *ar100;
 178         struct resource *r;
 179         struct clk *clk;
 180         int nparents;
 181         int i;
 182
 183         ar100 = devm_kzalloc(&pdev->dev, sizeof(*ar100), GFP_KERNEL);
 184         if (!ar100)
 185                 return -ENOMEM;
 186
 187         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 188         ar100->reg = devm_ioremap_resource(&pdev->dev, r);
 189         if (IS_ERR(ar100->reg))
 190                 return PTR_ERR(ar100->reg);
 191
 192         nparents = of_clk_get_parent_count(np);
 193         if (nparents > SUN6I_AR100_MAX_PARENTS)
 194                 nparents = SUN6I_AR100_MAX_PARENTS;
 195
 196         for (i = 0; i < nparents; i++)
 197                 parents[i] = of_clk_get_parent_name(np, i);
 198
 199         of_property_read_string(np, "clock-output-names", &clk_name);
 200
 201         init.name = clk_name;
 202         init.ops = &ar100_ops;
 203         init.parent_names = parents;
 204         init.num_parents = nparents;
 205         init.flags = 0;
 206
 207         ar100->hw.init = &init;
 208
 209         clk = clk_register(&pdev->dev, &ar100->hw);
 210         if (IS_ERR(clk))
 211                 return PTR_ERR(clk);
 212
 213         return of_clk_add_provider(np, of_clk_src_simple_get, clk);
 214 }
 215
 216 static const struct of_device_id sun6i_a31_ar100_clk_dt_ids[] = {
 217         { .compatible = "allwinner,sun6i-a31-ar100-clk" },
 218         { /* sentinel */ }
 219 };
 220
 221 static struct platform_driver sun6i_a31_ar100_clk_driver = {
 222         .driver = {
 223                 .name = "sun6i-a31-ar100-clk",
 224                 .owner = THIS_MODULE,
 225                 .of_match_table = sun6i_a31_ar100_clk_dt_ids,
 226         },
 227         .probe = sun6i_a31_ar100_clk_probe,
 228 };
 229 module_platform_driver(sun6i_a31_ar100_clk_driver);
 230
 231 MODULE_AUTHOR("Boris BREZILLON <boris.brezillon@free-electrons.com>");
 232 MODULE_DESCRIPTION("Allwinner A31 AR100 clock Driver");
 233 MODULE_LICENSE("GPL v2");