kernel/drivers/clk/qcom/clk-branch.c

   1 /*
   2  * Copyright (c) 2013, The Linux Foundation. All rights reserved.
   3  *
   4  * This software is licensed under the terms of the GNU General Public
   5  * License version 2, as published by the Free Software Foundation, and
   6  * may be copied, distributed, and modified under those terms.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  */
  13
  14 #include <linux/kernel.h>
  15 #include <linux/bitops.h>
  16 #include <linux/err.h>
  17 #include <linux/delay.h>
  18 #include <linux/export.h>
  19 #include <linux/clk-provider.h>
  20 #include <linux/regmap.h>
  21
  22 #include "clk-branch.h"
  23
  24 static bool clk_branch_in_hwcg_mode(const struct clk_branch *br)
  25 {
  26         u32 val;
  27
  28         if (!br->hwcg_reg)
  29                 return 0;
  30
  31         regmap_read(br->clkr.regmap, br->hwcg_reg, &val);
  32
  33         return !!(val & BIT(br->hwcg_bit));
  34 }
  35
  36 static bool clk_branch_check_halt(const struct clk_branch *br, bool enabling)
  37 {
  38         bool invert = (br->halt_check == BRANCH_HALT_ENABLE);
  39         u32 val;
  40
  41         regmap_read(br->clkr.regmap, br->halt_reg, &val);
  42
  43         val &= BIT(br->halt_bit);
  44         if (invert)
  45                 val = !val;
  46
  47         return !!val == !enabling;
  48 }
  49
  50 #define BRANCH_CLK_OFF                  BIT(31)
  51 #define BRANCH_NOC_FSM_STATUS_SHIFT     28
  52 #define BRANCH_NOC_FSM_STATUS_MASK      0x7
  53 #define BRANCH_NOC_FSM_STATUS_ON        (0x2 << BRANCH_NOC_FSM_STATUS_SHIFT)
  54
  55 static bool clk_branch2_check_halt(const struct clk_branch *br, bool enabling)
  56 {
  57         u32 val;
  58         u32 mask;
  59
  60         mask = BRANCH_NOC_FSM_STATUS_MASK << BRANCH_NOC_FSM_STATUS_SHIFT;
  61         mask |= BRANCH_CLK_OFF;
  62
  63         regmap_read(br->clkr.regmap, br->halt_reg, &val);
  64
  65         if (enabling) {
  66                 val &= mask;
  67                 return (val & BRANCH_CLK_OFF) == 0 ||
  68                         val == BRANCH_NOC_FSM_STATUS_ON;
  69         } else {
  70                 return val & BRANCH_CLK_OFF;
  71         }
  72 }
  73
  74 static int clk_branch_wait(const struct clk_branch *br, bool enabling,
  75                 bool (check_halt)(const struct clk_branch *, bool))
  76 {
  77         bool voted = br->halt_check & BRANCH_VOTED;
  78         const char *name = __clk_get_name(br->clkr.hw.clk);
  79
  80         /* Skip checking halt bit if the clock is in hardware gated mode */
  81         if (clk_branch_in_hwcg_mode(br))
  82                 return 0;
  83
  84         if (br->halt_check == BRANCH_HALT_DELAY || (!enabling && voted)) {
  85                 udelay(10);
  86         } else if (br->halt_check == BRANCH_HALT_ENABLE ||
  87                    br->halt_check == BRANCH_HALT ||
  88                    (enabling && voted)) {
  89                 int count = 200;
  90
  91                 while (count-- > 0) {
  92                         if (check_halt(br, enabling))
  93                                 return 0;
  94                         udelay(1);
  95                 }
  96                 WARN(1, "%s status stuck at 'o%s'", name,
  97                                 enabling ? "ff" : "n");
  98                 return -EBUSY;
  99         }
 100         return 0;
 101 }
 102
 103 static int clk_branch_toggle(struct clk_hw *hw, bool en,
 104                 bool (check_halt)(const struct clk_branch *, bool))
 105 {
 106         struct clk_branch *br = to_clk_branch(hw);
 107         int ret;
 108
 109         if (en) {
 110                 ret = clk_enable_regmap(hw);
 111                 if (ret)
 112                         return ret;
 113         } else {
 114                 clk_disable_regmap(hw);
 115         }
 116
 117         return clk_branch_wait(br, en, check_halt);
 118 }
 119
 120 static int clk_branch_enable(struct clk_hw *hw)
 121 {
 122         return clk_branch_toggle(hw, true, clk_branch_check_halt);
 123 }
 124
 125 static void clk_branch_disable(struct clk_hw *hw)
 126 {
 127         clk_branch_toggle(hw, false, clk_branch_check_halt);
 128 }
 129
 130 const struct clk_ops clk_branch_ops = {
 131         .enable = clk_branch_enable,
 132         .disable = clk_branch_disable,
 133         .is_enabled = clk_is_enabled_regmap,
 134 };
 135 EXPORT_SYMBOL_GPL(clk_branch_ops);
 136
 137 static int clk_branch2_enable(struct clk_hw *hw)
 138 {
 139         return clk_branch_toggle(hw, true, clk_branch2_check_halt);
 140 }
 141
 142 static void clk_branch2_disable(struct clk_hw *hw)
 143 {
 144         clk_branch_toggle(hw, false, clk_branch2_check_halt);
 145 }
 146
 147 const struct clk_ops clk_branch2_ops = {
 148         .enable = clk_branch2_enable,
 149         .disable = clk_branch2_disable,
 150         .is_enabled = clk_is_enabled_regmap,
 151 };
 152 EXPORT_SYMBOL_GPL(clk_branch2_ops);
 153
 154 const struct clk_ops clk_branch_simple_ops = {
 155         .enable = clk_enable_regmap,
 156         .disable = clk_disable_regmap,
 157         .is_enabled = clk_is_enabled_regmap,
 158 };
 159 EXPORT_SYMBOL_GPL(clk_branch_simple_ops);