drivers/clk/tegra/clk-periph-gate.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/clk.h>
  18 #include <linux/clk-provider.h>
  19 #include <linux/slab.h>
  20 #include <linux/io.h>
  21 #include <linux/delay.h>
  22 #include <linux/err.h>
  23 #include <linux/tegra-soc.h>
  24
  25 #include "clk.h"
  26
  27 static DEFINE_SPINLOCK(periph_ref_lock);
  28
  29 /* Macros to assist peripheral gate clock */
  30 #define read_enb(gate) \
  31         readl_relaxed(gate->clk_base + (gate->regs->enb_reg))
  32 #define write_enb_set(val, gate) \
  33         writel_relaxed(val, gate->clk_base + (gate->regs->enb_set_reg))
  34 #define write_enb_clr(val, gate) \
  35         writel_relaxed(val, gate->clk_base + (gate->regs->enb_clr_reg))
  36
  37 #define read_rst(gate) \
  38         readl_relaxed(gate->clk_base + (gate->regs->rst_reg))
  39 #define write_rst_clr(val, gate) \
  40         writel_relaxed(val, gate->clk_base + (gate->regs->rst_clr_reg))
  41
  42 #define periph_clk_to_bit(gate) (1 << (gate->clk_num % 32))
  43
  44 #define LVL2_CLK_GATE_OVRE 0x554
  45
  46 /* Peripheral gate clock ops */
  47 static int clk_periph_is_enabled(struct clk_hw *hw)
  48 {
  49         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
  50         int state = 1;
  51
  52         if (!(read_enb(gate) & periph_clk_to_bit(gate)))
  53                 state = 0;
  54
  55         if (!(gate->flags & TEGRA_PERIPH_NO_RESET))
  56                 if (read_rst(gate) & periph_clk_to_bit(gate))
  57                         state = 0;
  58
  59         return state;
  60 }
  61
  62 static int clk_periph_enable(struct clk_hw *hw)
  63 {
  64         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
  65         unsigned long flags = 0;
  66
  67         spin_lock_irqsave(&periph_ref_lock, flags);
  68
  69         gate->enable_refcnt[gate->clk_num]++;
  70         if (gate->enable_refcnt[gate->clk_num] > 1) {
  71                 spin_unlock_irqrestore(&periph_ref_lock, flags);
  72                 return 0;
  73         }
  74
  75         write_enb_set(periph_clk_to_bit(gate), gate);
  76         udelay(2);
  77
  78         if (!(gate->flags & TEGRA_PERIPH_NO_RESET) &&
  79             !(gate->flags & TEGRA_PERIPH_MANUAL_RESET)) {
  80                 if (read_rst(gate) & periph_clk_to_bit(gate)) {
  81                         udelay(5); /* reset propogation delay */
  82                         write_rst_clr(periph_clk_to_bit(gate), gate);
  83                 }
  84         }
  85
  86         if (gate->flags & TEGRA_PERIPH_WAR_1005168) {
  87                 writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
  88                 writel_relaxed(BIT(22), gate->clk_base + LVL2_CLK_GATE_OVRE);
  89                 udelay(1);
  90                 writel_relaxed(0, gate->clk_base + LVL2_CLK_GATE_OVRE);
  91         }
  92
  93         spin_unlock_irqrestore(&periph_ref_lock, flags);
  94
  95         return 0;
  96 }
  97
  98 static void clk_periph_disable(struct clk_hw *hw)
  99 {
 100         struct tegra_clk_periph_gate *gate = to_clk_periph_gate(hw);
 101         unsigned long flags = 0;
 102
 103         spin_lock_irqsave(&periph_ref_lock, flags);
 104
 105         gate->enable_refcnt[gate->clk_num]--;
 106         if (gate->enable_refcnt[gate->clk_num] > 0) {
 107                 spin_unlock_irqrestore(&periph_ref_lock, flags);
 108                 return;
 109         }
 110
 111         /*
 112          * If peripheral is in the APB bus then read the APB bus to
 113          * flush the write operation in apb bus. This will avoid the
 114          * peripheral access after disabling clock
 115          */
 116         if (gate->flags & TEGRA_PERIPH_ON_APB)
 117                 tegra_read_chipid();
 118
 119         write_enb_clr(periph_clk_to_bit(gate), gate);
 120
 121         spin_unlock_irqrestore(&periph_ref_lock, flags);
 122 }
 123
 124 const struct clk_ops tegra_clk_periph_gate_ops = {
 125         .is_enabled = clk_periph_is_enabled,
 126         .enable = clk_periph_enable,
 127         .disable = clk_periph_disable,
 128 };
 129
 130 struct clk *tegra_clk_register_periph_gate(const char *name,
 131                 const char *parent_name, u8 gate_flags, void __iomem *clk_base,
 132                 unsigned long flags, int clk_num, int *enable_refcnt)
 133 {
 134         struct tegra_clk_periph_gate *gate;
 135         struct clk *clk;
 136         struct clk_init_data init;
 137         struct tegra_clk_periph_regs *pregs;
 138
 139         pregs = get_reg_bank(clk_num);
 140         if (!pregs)
 141                 return ERR_PTR(-EINVAL);
 142
 143         gate = kzalloc(sizeof(*gate), GFP_KERNEL);
 144         if (!gate) {
 145                 pr_err("%s: could not allocate periph gate clk\n", __func__);
 146                 return ERR_PTR(-ENOMEM);
 147         }
 148
 149         init.name = name;
 150         init.flags = flags;
 151         init.parent_names = parent_name ? &parent_name : NULL;
 152         init.num_parents = parent_name ? 1 : 0;
 153         init.ops = &tegra_clk_periph_gate_ops;
 154
 155         gate->magic = TEGRA_CLK_PERIPH_GATE_MAGIC;
 156         gate->clk_base = clk_base;
 157         gate->clk_num = clk_num;
 158         gate->flags = gate_flags;
 159         gate->enable_refcnt = enable_refcnt;
 160         gate->regs = pregs;
 161
 162         /* Data in .init is copied by clk_register(), so stack variable OK */
 163         gate->hw.init = &init;
 164
 165         clk = clk_register(NULL, &gate->hw);
 166         if (IS_ERR(clk))
 167                 kfree(gate);
 168
 169         return clk;
 170 }