kernel/drivers/clk/meson/clk-cpu.c

   1 /*
   2  * Copyright (c) 2015 Endless Mobile, Inc.
   3  * Author: Carlo Caione <carlo@endlessm.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms and conditions of the GNU General Public License,
   7  * version 2, as published by the Free Software Foundation.
   8  *
   9  * This program is distributed in the hope it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  12  * more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along with
  15  * this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 /*
  19  * CPU clock path:
  20  *
  21  *                           +-[/N]-----|3|
  22  *             MUX2  +--[/3]-+----------|2| MUX1
  23  * [sys_pll]---|1|   |--[/2]------------|1|-|1|
  24  *             | |---+------------------|0| | |----- [a5_clk]
  25  *          +--|0|                          | |
  26  * [xtal]---+-------------------------------|0|
  27  *
  28  *
  29  *
  30  */
  31
  32 #include <linux/delay.h>
  33 #include <linux/err.h>
  34 #include <linux/io.h>
  35 #include <linux/module.h>
  36 #include <linux/of_address.h>
  37 #include <linux/slab.h>
  38 #include <linux/clk.h>
  39 #include <linux/clk-provider.h>
  40
  41 #define MESON_CPU_CLK_CNTL1             0x00
  42 #define MESON_CPU_CLK_CNTL              0x40
  43
  44 #define MESON_CPU_CLK_MUX1              BIT(7)
  45 #define MESON_CPU_CLK_MUX2              BIT(0)
  46
  47 #define MESON_N_WIDTH                   9
  48 #define MESON_N_SHIFT                   20
  49 #define MESON_SEL_WIDTH                 2
  50 #define MESON_SEL_SHIFT                 2
  51
  52 #include "clkc.h"
  53
  54 struct meson_clk_cpu {
  55         struct notifier_block           clk_nb;
  56         const struct clk_div_table      *div_table;
  57         struct clk_hw                   hw;
  58         void __iomem                    *base;
  59         u16                             reg_off;
  60 };
  61 #define to_meson_clk_cpu_hw(_hw) container_of(_hw, struct meson_clk_cpu, hw)
  62 #define to_meson_clk_cpu_nb(_nb) container_of(_nb, struct meson_clk_cpu, clk_nb)
  63
  64 static long meson_clk_cpu_round_rate(struct clk_hw *hw, unsigned long rate,
  65                                      unsigned long *prate)
  66 {
  67         struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
  68
  69         return divider_round_rate(hw, rate, prate, clk_cpu->div_table,
  70                                   MESON_N_WIDTH, CLK_DIVIDER_ROUND_CLOSEST);
  71 }
  72
  73 static int meson_clk_cpu_set_rate(struct clk_hw *hw, unsigned long rate,
  74                                   unsigned long parent_rate)
  75 {
  76         struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
  77         unsigned int div, sel, N = 0;
  78         u32 reg;
  79
  80         div = DIV_ROUND_UP(parent_rate, rate);
  81
  82         if (div <= 3) {
  83                 sel = div - 1;
  84         } else {
  85                 sel = 3;
  86                 N = div / 2;
  87         }
  88
  89         reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
  90         reg = PARM_SET(MESON_N_WIDTH, MESON_N_SHIFT, reg, N);
  91         writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
  92
  93         reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
  94         reg = PARM_SET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg, sel);
  95         writel(reg, clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
  96
  97         return 0;
  98 }
  99
 100 static unsigned long meson_clk_cpu_recalc_rate(struct clk_hw *hw,
 101                                                unsigned long parent_rate)
 102 {
 103         struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_hw(hw);
 104         unsigned int N, sel;
 105         unsigned int div = 1;
 106         u32 reg;
 107
 108         reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL1);
 109         N = PARM_GET(MESON_N_WIDTH, MESON_N_SHIFT, reg);
 110
 111         reg = readl(clk_cpu->base + clk_cpu->reg_off + MESON_CPU_CLK_CNTL);
 112         sel = PARM_GET(MESON_SEL_WIDTH, MESON_SEL_SHIFT, reg);
 113
 114         if (sel < 3)
 115                 div = sel + 1;
 116         else
 117                 div = 2 * N;
 118
 119         return parent_rate / div;
 120 }
 121
 122 static int meson_clk_cpu_pre_rate_change(struct meson_clk_cpu *clk_cpu,
 123                                          struct clk_notifier_data *ndata)
 124 {
 125         u32 cpu_clk_cntl;
 126
 127         /* switch MUX1 to xtal */
 128         cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
 129                                 + MESON_CPU_CLK_CNTL);
 130         cpu_clk_cntl &= ~MESON_CPU_CLK_MUX1;
 131         writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
 132                                 + MESON_CPU_CLK_CNTL);
 133         udelay(100);
 134
 135         /* switch MUX2 to sys-pll */
 136         cpu_clk_cntl |= MESON_CPU_CLK_MUX2;
 137         writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
 138                                 + MESON_CPU_CLK_CNTL);
 139
 140         return 0;
 141 }
 142
 143 static int meson_clk_cpu_post_rate_change(struct meson_clk_cpu *clk_cpu,
 144                                           struct clk_notifier_data *ndata)
 145 {
 146         u32 cpu_clk_cntl;
 147
 148         /* switch MUX1 to divisors' output */
 149         cpu_clk_cntl = readl(clk_cpu->base + clk_cpu->reg_off
 150                                 + MESON_CPU_CLK_CNTL);
 151         cpu_clk_cntl |= MESON_CPU_CLK_MUX1;
 152         writel(cpu_clk_cntl, clk_cpu->base + clk_cpu->reg_off
 153                                 + MESON_CPU_CLK_CNTL);
 154         udelay(100);
 155
 156         return 0;
 157 }
 158
 159 /*
 160  * This clock notifier is called when the frequency of the of the parent
 161  * PLL clock is to be changed. We use the xtal input as temporary parent
 162  * while the PLL frequency is stabilized.
 163  */
 164 static int meson_clk_cpu_notifier_cb(struct notifier_block *nb,
 165                                      unsigned long event, void *data)
 166 {
 167         struct clk_notifier_data *ndata = data;
 168         struct meson_clk_cpu *clk_cpu = to_meson_clk_cpu_nb(nb);
 169         int ret = 0;
 170
 171         if (event == PRE_RATE_CHANGE)
 172                 ret = meson_clk_cpu_pre_rate_change(clk_cpu, ndata);
 173         else if (event == POST_RATE_CHANGE)
 174                 ret = meson_clk_cpu_post_rate_change(clk_cpu, ndata);
 175
 176         return notifier_from_errno(ret);
 177 }
 178
 179 static const struct clk_ops meson_clk_cpu_ops = {
 180         .recalc_rate    = meson_clk_cpu_recalc_rate,
 181         .round_rate     = meson_clk_cpu_round_rate,
 182         .set_rate       = meson_clk_cpu_set_rate,
 183 };
 184
 185 struct clk *meson_clk_register_cpu(const struct clk_conf *clk_conf,
 186                                    void __iomem *reg_base,
 187                                    spinlock_t *lock)
 188 {
 189         struct clk *clk;
 190         struct clk *pclk;
 191         struct meson_clk_cpu *clk_cpu;
 192         struct clk_init_data init;
 193         int ret;
 194
 195         clk_cpu = kzalloc(sizeof(*clk_cpu), GFP_KERNEL);
 196         if (!clk_cpu)
 197                 return ERR_PTR(-ENOMEM);
 198
 199         clk_cpu->base = reg_base;
 200         clk_cpu->reg_off = clk_conf->reg_off;
 201         clk_cpu->div_table = clk_conf->conf.div_table;
 202         clk_cpu->clk_nb.notifier_call = meson_clk_cpu_notifier_cb;
 203
 204         init.name = clk_conf->clk_name;
 205         init.ops = &meson_clk_cpu_ops;
 206         init.flags = clk_conf->flags | CLK_GET_RATE_NOCACHE;
 207         init.flags |= CLK_SET_RATE_PARENT;
 208         init.parent_names = clk_conf->clks_parent;
 209         init.num_parents = 1;
 210
 211         clk_cpu->hw.init = &init;
 212
 213         pclk = __clk_lookup(clk_conf->clks_parent[0]);
 214         if (!pclk) {
 215                 pr_err("%s: could not lookup parent clock %s\n",
 216                                 __func__, clk_conf->clks_parent[0]);
 217                 ret = -EINVAL;
 218                 goto free_clk;
 219         }
 220
 221         ret = clk_notifier_register(pclk, &clk_cpu->clk_nb);
 222         if (ret) {
 223                 pr_err("%s: failed to register clock notifier for %s\n",
 224                                 __func__, clk_conf->clk_name);
 225                 goto free_clk;
 226         }
 227
 228         clk = clk_register(NULL, &clk_cpu->hw);
 229         if (IS_ERR(clk)) {
 230                 ret = PTR_ERR(clk);
 231                 goto unregister_clk_nb;
 232         }
 233
 234         return clk;
 235
 236 unregister_clk_nb:
 237         clk_notifier_unregister(pclk, &clk_cpu->clk_nb);
 238 free_clk:
 239         kfree(clk_cpu);
 240
 241         return ERR_PTR(ret);
 242 }
 243