drivers/clk/at91/clk-system.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/of.h>
  15 #include <linux/of_address.h>
  16 #include <linux/io.h>
  17 #include <linux/irq.h>
  18 #include <linux/of_irq.h>
  19 #include <linux/interrupt.h>
  20 #include <linux/wait.h>
  21 #include <linux/sched.h>
  22
  23 #include "pmc.h"
  24
  25 #define SYSTEM_MAX_ID           31
  26
  27 #define SYSTEM_MAX_NAME_SZ      32
  28
  29 #define to_clk_system(hw) container_of(hw, struct clk_system, hw)
  30 struct clk_system {
  31         struct clk_hw hw;
  32         struct at91_pmc *pmc;
  33         unsigned int irq;
  34         wait_queue_head_t wait;
  35         u8 id;
  36 };
  37
  38 static inline int is_pck(int id)
  39 {
  40         return (id >= 8) && (id <= 15);
  41 }
  42 static irqreturn_t clk_system_irq_handler(int irq, void *dev_id)
  43 {
  44         struct clk_system *sys = (struct clk_system *)dev_id;
  45
  46         wake_up(&sys->wait);
  47         disable_irq_nosync(sys->irq);
  48
  49         return IRQ_HANDLED;
  50 }
  51
  52 static int clk_system_prepare(struct clk_hw *hw)
  53 {
  54         struct clk_system *sys = to_clk_system(hw);
  55         struct at91_pmc *pmc = sys->pmc;
  56         u32 mask = 1 << sys->id;
  57
  58         pmc_write(pmc, AT91_PMC_SCER, mask);
  59
  60         if (!is_pck(sys->id))
  61                 return 0;
  62
  63         while (!(pmc_read(pmc, AT91_PMC_SR) & mask)) {
  64                 if (sys->irq) {
  65                         enable_irq(sys->irq);
  66                         wait_event(sys->wait,
  67                                    pmc_read(pmc, AT91_PMC_SR) & mask);
  68                 } else
  69                         cpu_relax();
  70         }
  71         return 0;
  72 }
  73
  74 static void clk_system_unprepare(struct clk_hw *hw)
  75 {
  76         struct clk_system *sys = to_clk_system(hw);
  77         struct at91_pmc *pmc = sys->pmc;
  78
  79         pmc_write(pmc, AT91_PMC_SCDR, 1 << sys->id);
  80 }
  81
  82 static int clk_system_is_prepared(struct clk_hw *hw)
  83 {
  84         struct clk_system *sys = to_clk_system(hw);
  85         struct at91_pmc *pmc = sys->pmc;
  86
  87         if (!(pmc_read(pmc, AT91_PMC_SCSR) & (1 << sys->id)))
  88                 return 0;
  89
  90         if (!is_pck(sys->id))
  91                 return 1;
  92
  93         return !!(pmc_read(pmc, AT91_PMC_SR) & (1 << sys->id));
  94 }
  95
  96 static const struct clk_ops system_ops = {
  97         .prepare = clk_system_prepare,
  98         .unprepare = clk_system_unprepare,
  99         .is_prepared = clk_system_is_prepared,
 100 };
 101
 102 static struct clk * __init
 103 at91_clk_register_system(struct at91_pmc *pmc, const char *name,
 104                          const char *parent_name, u8 id, int irq)
 105 {
 106         struct clk_system *sys;
 107         struct clk *clk = NULL;
 108         struct clk_init_data init;
 109         int ret;
 110
 111         if (!parent_name || id > SYSTEM_MAX_ID)
 112                 return ERR_PTR(-EINVAL);
 113
 114         sys = kzalloc(sizeof(*sys), GFP_KERNEL);
 115         if (!sys)
 116                 return ERR_PTR(-ENOMEM);
 117
 118         init.name = name;
 119         init.ops = &system_ops;
 120         init.parent_names = &parent_name;
 121         init.num_parents = 1;
 122         /*
 123          * CLK_IGNORE_UNUSED is used to avoid ddrck switch off.
 124          * TODO : we should implement a driver supporting at91 ddr controller
 125          * (see drivers/memory) which would request and enable the ddrck clock.
 126          * When this is done we will be able to remove CLK_IGNORE_UNUSED flag.
 127          */
 128         init.flags = CLK_SET_RATE_PARENT | CLK_IGNORE_UNUSED;
 129
 130         sys->id = id;
 131         sys->hw.init = &init;
 132         sys->pmc = pmc;
 133         sys->irq = irq;
 134         if (irq) {
 135                 init_waitqueue_head(&sys->wait);
 136                 irq_set_status_flags(sys->irq, IRQ_NOAUTOEN);
 137                 ret = request_irq(sys->irq, clk_system_irq_handler,
 138                                 IRQF_TRIGGER_HIGH, name, sys);
 139                 if (ret)
 140                         return ERR_PTR(ret);
 141         }
 142
 143         clk = clk_register(NULL, &sys->hw);
 144         if (IS_ERR(clk))
 145                 kfree(sys);
 146
 147         return clk;
 148 }
 149
 150 static void __init
 151 of_at91_clk_sys_setup(struct device_node *np, struct at91_pmc *pmc)
 152 {
 153         int num;
 154         int irq = 0;
 155         u32 id;
 156         struct clk *clk;
 157         const char *name;
 158         struct device_node *sysclknp;
 159         const char *parent_name;
 160
 161         num = of_get_child_count(np);
 162         if (num > (SYSTEM_MAX_ID + 1))
 163                 return;
 164
 165         for_each_child_of_node(np, sysclknp) {
 166                 if (of_property_read_u32(sysclknp, "reg", &id))
 167                         continue;
 168
 169                 if (of_property_read_string(np, "clock-output-names", &name))
 170                         name = sysclknp->name;
 171
 172                 if (is_pck(id))
 173                         irq = irq_of_parse_and_map(sysclknp, 0);
 174
 175                 parent_name = of_clk_get_parent_name(sysclknp, 0);
 176
 177                 clk = at91_clk_register_system(pmc, name, parent_name, id, irq);
 178                 if (IS_ERR(clk))
 179                         continue;
 180
 181                 of_clk_add_provider(sysclknp, of_clk_src_simple_get, clk);
 182         }
 183 }
 184
 185 void __init of_at91rm9200_clk_sys_setup(struct device_node *np,
 186                                         struct at91_pmc *pmc)
 187 {
 188         of_at91_clk_sys_setup(np, pmc);
 189 }