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Linux/drivers/clocksource/dw_apb_timer_of.c

  1 /*
  2  * Copyright (C) 2012 Altera Corporation
  3  * Copyright (c) 2011 Picochip Ltd., Jamie Iles
  4  *
  5  * Modified from mach-picoxcell/time.c
  6  *
  7  * This program is free software; you can redistribute it and/or modify
  8  * it under the terms of the GNU General Public License version 2 as
  9  * published by the Free Software Foundation.
 10  *
 11  * This program is distributed in the hope that it will be useful,
 12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 14  * GNU General Public License for more details.
 15  *
 16  * You should have received a copy of the GNU General Public License
 17  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 18  */
 19 #include <linux/dw_apb_timer.h>
 20 #include <linux/of.h>
 21 #include <linux/of_address.h>
 22 #include <linux/of_irq.h>
 23 #include <linux/clk.h>
 24 #include <linux/sched_clock.h>
 25 
 26 static void __init timer_get_base_and_rate(struct device_node *np,
 27                                     void __iomem **base, u32 *rate)
 28 {
 29         struct clk *timer_clk;
 30         struct clk *pclk;
 31 
 32         *base = of_iomap(np, 0);
 33 
 34         if (!*base)
 35                 panic("Unable to map regs for %s", np->name);
 36 
 37         /*
 38          * Not all implementations use a periphal clock, so don't panic
 39          * if it's not present
 40          */
 41         pclk = of_clk_get_by_name(np, "pclk");
 42         if (!IS_ERR(pclk))
 43                 if (clk_prepare_enable(pclk))
 44                         pr_warn("pclk for %s is present, but could not be activated\n",
 45                                 np->name);
 46 
 47         timer_clk = of_clk_get_by_name(np, "timer");
 48         if (IS_ERR(timer_clk))
 49                 goto try_clock_freq;
 50 
 51         if (!clk_prepare_enable(timer_clk)) {
 52                 *rate = clk_get_rate(timer_clk);
 53                 return;
 54         }
 55 
 56 try_clock_freq:
 57         if (of_property_read_u32(np, "clock-freq", rate) &&
 58             of_property_read_u32(np, "clock-frequency", rate))
 59                 panic("No clock nor clock-frequency property for %s", np->name);
 60 }
 61 
 62 static void __init add_clockevent(struct device_node *event_timer)
 63 {
 64         void __iomem *iobase;
 65         struct dw_apb_clock_event_device *ced;
 66         u32 irq, rate;
 67 
 68         irq = irq_of_parse_and_map(event_timer, 0);
 69         if (irq == 0)
 70                 panic("No IRQ for clock event timer");
 71 
 72         timer_get_base_and_rate(event_timer, &iobase, &rate);
 73 
 74         ced = dw_apb_clockevent_init(0, event_timer->name, 300, iobase, irq,
 75                                      rate);
 76         if (!ced)
 77                 panic("Unable to initialise clockevent device");
 78 
 79         dw_apb_clockevent_register(ced);
 80 }
 81 
 82 static void __iomem *sched_io_base;
 83 static u32 sched_rate;
 84 
 85 static void __init add_clocksource(struct device_node *source_timer)
 86 {
 87         void __iomem *iobase;
 88         struct dw_apb_clocksource *cs;
 89         u32 rate;
 90 
 91         timer_get_base_and_rate(source_timer, &iobase, &rate);
 92 
 93         cs = dw_apb_clocksource_init(300, source_timer->name, iobase, rate);
 94         if (!cs)
 95                 panic("Unable to initialise clocksource device");
 96 
 97         dw_apb_clocksource_start(cs);
 98         dw_apb_clocksource_register(cs);
 99 
100         /*
101          * Fallback to use the clocksource as sched_clock if no separate
102          * timer is found. sched_io_base then points to the current_value
103          * register of the clocksource timer.
104          */
105         sched_io_base = iobase + 0x04;
106         sched_rate = rate;
107 }
108 
109 static u64 notrace read_sched_clock(void)
110 {
111         return ~__raw_readl(sched_io_base);
112 }
113 
114 static const struct of_device_id sptimer_ids[] __initconst = {
115         { .compatible = "picochip,pc3x2-rtc" },
116         { /* Sentinel */ },
117 };
118 
119 static void __init init_sched_clock(void)
120 {
121         struct device_node *sched_timer;
122 
123         sched_timer = of_find_matching_node(NULL, sptimer_ids);
124         if (sched_timer) {
125                 timer_get_base_and_rate(sched_timer, &sched_io_base,
126                                         &sched_rate);
127                 of_node_put(sched_timer);
128         }
129 
130         sched_clock_register(read_sched_clock, 32, sched_rate);
131 }
132 
133 static int num_called;
134 static void __init dw_apb_timer_init(struct device_node *timer)
135 {
136         switch (num_called) {
137         case 0:
138                 pr_debug("%s: found clockevent timer\n", __func__);
139                 add_clockevent(timer);
140                 break;
141         case 1:
142                 pr_debug("%s: found clocksource timer\n", __func__);
143                 add_clocksource(timer);
144                 init_sched_clock();
145                 break;
146         default:
147                 break;
148         }
149 
150         num_called++;
151 }
152 CLOCKSOURCE_OF_DECLARE(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);
153 CLOCKSOURCE_OF_DECLARE(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
154 CLOCKSOURCE_OF_DECLARE(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
155 CLOCKSOURCE_OF_DECLARE(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);
156 

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