drivers/clk/tegra/clk-periph-gate.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2012, NVIDIA CORPORATION.  All rights reserved.
   4  */
   5
   6 #include <linux/clk-provider.h>
   7 #include <linux/slab.h>
   8 #include <linux/io.h>
   9 #include <linux/delay.h>
  10 #include <linux/err.h>
  11
  12 #include <soc/tegra/fuse.h>
  13
  14 #include "clk.h"
  15
  16 static DEFINE_SPINLOCK(periph_ref_lock);
  17
  18 /* Macros to assist peripheral gate clock */
  19 #define read_enb(gate) \
  20         readl_relaxed(gate->clk_base + (gate->regs->enb_reg))
  21 #define write_enb_set(val, gate) \
  22         writel_relaxed(val, gate->clk_base + (gate->regs->enb_set_reg))
  23 #define write_enb_clr(val, gate) \
  24         writel_relaxed(val, gate->clk_base + (gate->regs->enb_clr_reg))
  25
  26 #define read_rst(gate) \
  27         readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
  28 #define write_rst_clr(val, gate) \
  29         writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
  30
  31 #define periph_clk_to_bit(gate) (1 << (gate->clk_num % 32))
  32
  33 #define LVL2_CLK_GATE_OVRE 0x554
  34
  35 /* Peripheral gate clock ops */
  36 static int clk_periph_is_enabled(struct clk_hw *hw)
  37 {
  38         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
  39         int state = 1;
  40
  41         if (!(read_enb(gate) & periph_clk_to_bit(gate)))
  42                 state = 0;
  43
  44         if (!(gate->flags & TEGRA_PERIPH_NO_RESET))
  45                 if (read_rst(gate) & periph_clk_to_bit(gate))
  46                         state = 0;
  47
  48         return state;
  49 }
  50
  51 static int clk_periph_enable(struct clk_hw *hw)
  52 {
  53         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
  54         unsigned long flags = 0;
  55
  56         spin_lock_irqsave(&periph_ref_lock, flags);
  57
  58         gate->enable_refcnt[gate->clk_num]++;
  59         if (gate->enable_refcnt[gate->clk_num] > 1) {
  60                 spin_unlock_irqrestore(&periph_ref_lock, flags);
  61                 return 0;
  62         }
  63
  64         write_enb_set(periph_clk_to_bit(gate), gate);
  65         udelay(2);
  66
  67         if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
  68             !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
  69                 if (read_rst(gate) & periph_clk_to_bit(gate)) {
  70                         udelay(5); /* reset propogation delay */
  71                         write_rst_clr(periph_clk_to_bit(gate), gate);
  72                 }
  73         }
  74
  75         if (gate->flags & TEGRA_PERIPH_WAR_1005168) {
  76                 writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
  77                 writel_relaxed(BIT(22), gate->clk_base + LVL2_CLK_GATE_OVRE);
  78                 udelay(1);
  79                 writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
  80         }
  81
  82         spin_unlock_irqrestore(&periph_ref_lock, flags);
  83
  84         return 0;
  85 }
  86
  87 static void clk_periph_disable(struct clk_hw *hw)
  88 {
  89         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
  90         unsigned long flags = 0;
  91
  92         spin_lock_irqsave(&periph_ref_lock, flags);
  93
  94         gate->enable_refcnt[gate->clk_num]--;
  95         if (gate->enable_refcnt[gate->clk_num] > 0) {
  96                 spin_unlock_irqrestore(&periph_ref_lock, flags);
  97                 return;
  98         }
  99
 100         /*
 101          * If peripheral is in the APB bus then read the APB bus to
 102          * flush the write operation in apb bus. This will avoid the
 103          * peripheral access after disabling clock
 104          */
 105         if (gate->flags & TEGRA_PERIPH_ON_APB)
 106                 tegra_read_chipid();
 107
 108         write_enb_clr(periph_clk_to_bit(gate), gate);
 109
 110         spin_unlock_irqrestore(&periph_ref_lock, flags);
 111 }
 112
 113 const struct clk_ops tegra_clk_periph_gate_ops = {
 114         .is_enabled = clk_periph_is_enabled,
 115         .enable = clk_periph_enable,
 116         .disable = clk_periph_disable,
 117 };
 118
 119 struct clk *tegra_clk_register_periph_gate(const char *name,
 120                 const char *parent_name, u8 gate_flags, void __iomem *clk_base,
 121                 unsigned long flags, int clk_num, int *enable_refcnt)
 122 {
 123         struct tegra_clk_periph_gate *gate;
 124         struct clk *clk;
 125         struct clk_init_data init;
 126         const struct tegra_clk_periph_regs *pregs;
 127
 128         pregs = get_reg_bank(clk_num);
 129         if (!pregs)
 130                 return ERR_PTR(-EINVAL);
 131
 132         gate = kzalloc(sizeof(*gate), GFP_KERNEL);
 133         if (!gate) {
 134                 pr_err("%s: could not allocate periph gate clk\n", __func__);
 135                 return ERR_PTR(-ENOMEM);
 136         }
 137
 138         init.name = name;
 139         init.flags = flags;
 140         init.parent_names = parent_name ? &parent_name : NULL;
 141         init.num_parents = parent_name ? 1 : 0;
 142         init.ops = &tegra_clk_periph_gate_ops;
 143
 144         gate->magic = TEGRA_CLK_PERIPH_GATE_MAGIC;
 145         gate->clk_base = clk_base;
 146         gate->clk_num = clk_num;
 147         gate->flags = gate_flags;
 148         gate->enable_refcnt = enable_refcnt;
 149         gate->regs = pregs;
 150
 151         if (read_enb(gate) & periph_clk_to_bit(gate))
 152                 enable_refcnt[clk_num]++;
 153
 154         /* Data in .init is copied by clk_register(), so stack variable OK */
 155         gate->hw.init = &init;
 156
 157         clk = clk_register(NULL, &gate->hw);
 158         if (IS_ERR(clk))
 159                 kfree(gate);
 160
 161         return clk;
 162 }