drivers/clk/at91/clk-main.c

   1 /*
   2  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/clkdev.h>
  13 #include <linux/clk/at91_pmc.h>
  14 #include <linux/delay.h>
  15 #include <linux/of.h>
  16 #include <linux/of_address.h>
  17 #include <linux/of_irq.h>
  18 #include <linux/io.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/irq.h>
  21 #include <linux/sched.h>
  22 #include <linux/wait.h>
  23
  24 #include "pmc.h"
  25
  26 #define SLOW_CLOCK_FREQ         32768
  27 #define MAINF_DIV               16
  28 #define MAINFRDY_TIMEOUT        (((MAINF_DIV + 1) * USEC_PER_SEC) / \
  29                                  SLOW_CLOCK_FREQ)
  30 #define MAINF_LOOP_MIN_WAIT     (USEC_PER_SEC / SLOW_CLOCK_FREQ)
  31 #define MAINF_LOOP_MAX_WAIT     MAINFRDY_TIMEOUT
  32
  33 struct clk_main {
  34         struct clk_hw hw;
  35         struct at91_pmc *pmc;
  36         unsigned long rate;
  37         unsigned int irq;
  38         wait_queue_head_t wait;
  39 };
  40
  41 #define to_clk_main(hw) container_of(hw, struct clk_main, hw)
  42
  43 static irqreturn_t clk_main_irq_handler(int irq, void *dev_id)
  44 {
  45         struct clk_main *clkmain = (struct clk_main *)dev_id;
  46
  47         wake_up(&clkmain->wait);
  48         disable_irq_nosync(clkmain->irq);
  49
  50         return IRQ_HANDLED;
  51 }
  52
  53 static int clk_main_prepare(struct clk_hw *hw)
  54 {
  55         struct clk_main *clkmain = to_clk_main(hw);
  56         struct at91_pmc *pmc = clkmain->pmc;
  57         unsigned long halt_time, timeout;
  58         u32 tmp;
  59
  60         while (!(pmc_read(pmc, AT91_PMC_SR) & AT91_PMC_MOSCS)) {
  61                 enable_irq(clkmain->irq);
  62                 wait_event(clkmain->wait,
  63                            pmc_read(pmc, AT91_PMC_SR) & AT91_PMC_MOSCS);
  64         }
  65
  66         if (clkmain->rate)
  67                 return 0;
  68
  69         timeout = jiffies + usecs_to_jiffies(MAINFRDY_TIMEOUT);
  70         do {
  71                 halt_time = jiffies;
  72                 tmp = pmc_read(pmc, AT91_CKGR_MCFR);
  73                 if (tmp & AT91_PMC_MAINRDY)
  74                         return 0;
  75                 usleep_range(MAINF_LOOP_MIN_WAIT, MAINF_LOOP_MAX_WAIT);
  76         } while (time_before(halt_time, timeout));
  77
  78         return 0;
  79 }
  80
  81 static int clk_main_is_prepared(struct clk_hw *hw)
  82 {
  83         struct clk_main *clkmain = to_clk_main(hw);
  84
  85         return !!(pmc_read(clkmain->pmc, AT91_PMC_SR) & AT91_PMC_MOSCS);
  86 }
  87
  88 static unsigned long clk_main_recalc_rate(struct clk_hw *hw,
  89                                           unsigned long parent_rate)
  90 {
  91         u32 tmp;
  92         struct clk_main *clkmain = to_clk_main(hw);
  93         struct at91_pmc *pmc = clkmain->pmc;
  94
  95         if (clkmain->rate)
  96                 return clkmain->rate;
  97
  98         tmp = pmc_read(pmc, AT91_CKGR_MCFR) & AT91_PMC_MAINF;
  99         clkmain->rate = (tmp * parent_rate) / MAINF_DIV;
 100
 101         return clkmain->rate;
 102 }
 103
 104 static const struct clk_ops main_ops = {
 105         .prepare = clk_main_prepare,
 106         .is_prepared = clk_main_is_prepared,
 107         .recalc_rate = clk_main_recalc_rate,
 108 };
 109
 110 static struct clk * __init
 111 at91_clk_register_main(struct at91_pmc *pmc,
 112                        unsigned int irq,
 113                        const char *name,
 114                        const char *parent_name,
 115                        unsigned long rate)
 116 {
 117         int ret;
 118         struct clk_main *clkmain;
 119         struct clk *clk = NULL;
 120         struct clk_init_data init;
 121
 122         if (!pmc || !irq || !name)
 123                 return ERR_PTR(-EINVAL);
 124
 125         if (!rate && !parent_name)
 126                 return ERR_PTR(-EINVAL);
 127
 128         clkmain = kzalloc(sizeof(*clkmain), GFP_KERNEL);
 129         if (!clkmain)
 130                 return ERR_PTR(-ENOMEM);
 131
 132         init.name = name;
 133         init.ops = &main_ops;
 134         init.parent_names = parent_name ? &parent_name : NULL;
 135         init.num_parents = parent_name ? 1 : 0;
 136         init.flags = parent_name ? 0 : CLK_IS_ROOT;
 137
 138         clkmain->hw.init = &init;
 139         clkmain->rate = rate;
 140         clkmain->pmc = pmc;
 141         clkmain->irq = irq;
 142         init_waitqueue_head(&clkmain->wait);
 143         irq_set_status_flags(clkmain->irq, IRQ_NOAUTOEN);
 144         ret = request_irq(clkmain->irq, clk_main_irq_handler,
 145                           IRQF_TRIGGER_HIGH, "clk-main", clkmain);
 146         if (ret)
 147                 return ERR_PTR(ret);
 148
 149         clk = clk_register(NULL, &clkmain->hw);
 150         if (IS_ERR(clk)) {
 151                 free_irq(clkmain->irq, clkmain);
 152                 kfree(clkmain);
 153         }
 154
 155         return clk;
 156 }
 157
 158
 159
 160 static void __init
 161 of_at91_clk_main_setup(struct device_node *np, struct at91_pmc *pmc)
 162 {
 163         struct clk *clk;
 164         unsigned int irq;
 165         const char *parent_name;
 166         const char *name = np->name;
 167         u32 rate = 0;
 168
 169         parent_name = of_clk_get_parent_name(np, 0);
 170         of_property_read_string(np, "clock-output-names", &name);
 171         of_property_read_u32(np, "clock-frequency", &rate);
 172         irq = irq_of_parse_and_map(np, 0);
 173         if (!irq)
 174                 return;
 175
 176         clk = at91_clk_register_main(pmc, irq, name, parent_name, rate);
 177         if (IS_ERR(clk))
 178                 return;
 179
 180         of_clk_add_provider(np, of_clk_src_simple_get, clk);
 181 }
 182
 183 void __init of_at91rm9200_clk_main_setup(struct device_node *np,
 184                                          struct at91_pmc *pmc)
 185 {
 186         of_at91_clk_main_setup(np, pmc);
 187 }