drivers/clk/tegra/clk-divider.c

   1 /*
   2  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms and conditions of the GNU General Public License,
   6  * version 2, as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/io.h>
  19 #include <linux/err.h>
  20 #include <linux/slab.h>
  21 #include <linux/clk-provider.h>
  22 #include <linux/clk.h>
  23
  24 #include "clk.h"
  25
  26 #define pll_out_override(p) (BIT((p->shift - 6)))
  27 #define div_mask(d) ((1 << (d->width)) - 1)
  28 #define get_mul(d) (1 << d->frac_width)
  29 #define get_max_div(d) div_mask(d)
  30
  31 #define PERIPH_CLK_UART_DIV_ENB BIT(24)
  32
  33 static int get_div(struct tegra_clk_frac_div *divider, unsigned long rate,
  34                    unsigned long parent_rate)
  35 {
  36         s64 divider_ux1 = parent_rate;
  37         u8 flags = divider->flags;
  38         int mul;
  39
  40         if (!rate)
  41                 return 0;
  42
  43         mul = get_mul(divider);
  44
  45         if (!(flags & TEGRA_DIVIDER_INT))
  46                 divider_ux1 *= mul;
  47
  48         if (flags & TEGRA_DIVIDER_ROUND_UP)
  49                 divider_ux1 += rate - 1;
  50
  51         do_div(divider_ux1, rate);
  52
  53         if (flags & TEGRA_DIVIDER_INT)
  54                 divider_ux1 *= mul;
  55
  56         divider_ux1 -= mul;
  57
  58         if (divider_ux1 < 0)
  59                 return 0;
  60
  61         if (divider_ux1 > get_max_div(divider))
  62                 return -EINVAL;
  63
  64         return divider_ux1;
  65 }
  66
  67 static unsigned long clk_frac_div_recalc_rate(struct clk_hw *hw,
  68                                              unsigned long parent_rate)
  69 {
  70         struct tegra_clk_frac_div *divider = to_clk_frac_div(hw);
  71         u32 reg;
  72         int div, mul;
  73         u64 rate = parent_rate;
  74
  75         reg = readl_relaxed(divider->reg) >> divider->shift;
  76         div = reg & div_mask(divider);
  77
  78         mul = get_mul(divider);
  79         div += mul;
  80
  81         rate *= mul;
  82         rate += div - 1;
  83         do_div(rate, div);
  84
  85         return rate;
  86 }
  87
  88 static long clk_frac_div_round_rate(struct clk_hw *hw, unsigned long rate,
  89                                    unsigned long *prate)
  90 {
  91         struct tegra_clk_frac_div *divider = to_clk_frac_div(hw);
  92         int div, mul;
  93         unsigned long output_rate = *prate;
  94
  95         if (!rate)
  96                 return output_rate;
  97
  98         div = get_div(divider, rate, output_rate);
  99         if (div < 0)
 100                 return *prate;
 101
 102         mul = get_mul(divider);
 103
 104         return DIV_ROUND_UP(output_rate * mul, div + mul);
 105 }
 106
 107 static int clk_frac_div_set_rate(struct clk_hw *hw, unsigned long rate,
 108                                 unsigned long parent_rate)
 109 {
 110         struct tegra_clk_frac_div *divider = to_clk_frac_div(hw);
 111         int div;
 112         unsigned long flags = 0;
 113         u32 val;
 114
 115         div = get_div(divider, rate, parent_rate);
 116         if (div < 0)
 117                 return div;
 118
 119         if (divider->lock)
 120                 spin_lock_irqsave(divider->lock, flags);
 121
 122         val = readl_relaxed(divider->reg);
 123         val &= ~(div_mask(divider) << divider->shift);
 124         val |= div << divider->shift;
 125
 126         if (divider->flags & TEGRA_DIVIDER_UART) {
 127                 if (div)
 128                         val |= PERIPH_CLK_UART_DIV_ENB;
 129                 else
 130                         val &= ~PERIPH_CLK_UART_DIV_ENB;
 131         }
 132
 133         if (divider->flags & TEGRA_DIVIDER_FIXED)
 134                 val |= pll_out_override(divider);
 135
 136         writel_relaxed(val, divider->reg);
 137
 138         if (divider->lock)
 139                 spin_unlock_irqrestore(divider->lock, flags);
 140
 141         return 0;
 142 }
 143
 144 const struct clk_ops tegra_clk_frac_div_ops = {
 145         .recalc_rate = clk_frac_div_recalc_rate,
 146         .set_rate = clk_frac_div_set_rate,
 147         .round_rate = clk_frac_div_round_rate,
 148 };
 149
 150 struct clk *tegra_clk_register_divider(const char *name,
 151                 const char *parent_name, void __iomem *reg,
 152                 unsigned long flags, u8 clk_divider_flags, u8 shift, u8 width,
 153                 u8 frac_width, spinlock_t *lock)
 154 {
 155         struct tegra_clk_frac_div *divider;
 156         struct clk *clk;
 157         struct clk_init_data init;
 158
 159         divider = kzalloc(sizeof(*divider), GFP_KERNEL);
 160         if (!divider) {
 161                 pr_err("%s: could not allocate fractional divider clk\n",
 162                        __func__);
 163                 return ERR_PTR(-ENOMEM);
 164         }
 165
 166         init.name = name;
 167         init.ops = &tegra_clk_frac_div_ops;
 168         init.flags = flags;
 169         init.parent_names = parent_name ? &parent_name : NULL;
 170         init.num_parents = parent_name ? 1 : 0;
 171
 172         divider->reg = reg;
 173         divider->shift = shift;
 174         divider->width = width;
 175         divider->frac_width = frac_width;
 176         divider->lock = lock;
 177         divider->flags = clk_divider_flags;
 178
 179         /* Data in .init is copied by clk_register(), so stack variable OK */
 180         divider->hw.init = &init;
 181
 182         clk = clk_register(NULL, &divider->hw);
 183         if (IS_ERR(clk))
 184                 kfree(divider);
 185
 186         return clk;
 187 }