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Linux/arch/mips/ralink/cevt-rt3352.c

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  1 /*
  2  * This file is subject to the terms and conditions of the GNU General Public
  3  * License.  See the file "COPYING" in the main directory of this archive
  4  * for more details.
  5  *
  6  * Copyright (C) 2013 by John Crispin <john@phrozen.org>
  7  */
  8 
  9 #include <linux/clockchips.h>
 10 #include <linux/clocksource.h>
 11 #include <linux/interrupt.h>
 12 #include <linux/reset.h>
 13 #include <linux/init.h>
 14 #include <linux/time.h>
 15 #include <linux/of.h>
 16 #include <linux/of_irq.h>
 17 #include <linux/of_address.h>
 18 
 19 #include <asm/mach-ralink/ralink_regs.h>
 20 
 21 #define SYSTICK_FREQ            (50 * 1000)
 22 
 23 #define SYSTICK_CONFIG          0x00
 24 #define SYSTICK_COMPARE         0x04
 25 #define SYSTICK_COUNT           0x08
 26 
 27 /* route systick irq to mips irq 7 instead of the r4k-timer */
 28 #define CFG_EXT_STK_EN          0x2
 29 /* enable the counter */
 30 #define CFG_CNT_EN              0x1
 31 
 32 struct systick_device {
 33         void __iomem *membase;
 34         struct clock_event_device dev;
 35         int irq_requested;
 36         int freq_scale;
 37 };
 38 
 39 static int systick_set_oneshot(struct clock_event_device *evt);
 40 static int systick_shutdown(struct clock_event_device *evt);
 41 
 42 static int systick_next_event(unsigned long delta,
 43                                 struct clock_event_device *evt)
 44 {
 45         struct systick_device *sdev;
 46         u32 count;
 47 
 48         sdev = container_of(evt, struct systick_device, dev);
 49         count = ioread32(sdev->membase + SYSTICK_COUNT);
 50         count = (count + delta) % SYSTICK_FREQ;
 51         iowrite32(count, sdev->membase + SYSTICK_COMPARE);
 52 
 53         return 0;
 54 }
 55 
 56 static void systick_event_handler(struct clock_event_device *dev)
 57 {
 58         /* noting to do here */
 59 }
 60 
 61 static irqreturn_t systick_interrupt(int irq, void *dev_id)
 62 {
 63         struct clock_event_device *dev = (struct clock_event_device *) dev_id;
 64 
 65         dev->event_handler(dev);
 66 
 67         return IRQ_HANDLED;
 68 }
 69 
 70 static struct systick_device systick = {
 71         .dev = {
 72                 /*
 73                  * cevt-r4k uses 300, make sure systick
 74                  * gets used if available
 75                  */
 76                 .rating                 = 310,
 77                 .features               = CLOCK_EVT_FEAT_ONESHOT,
 78                 .set_next_event         = systick_next_event,
 79                 .set_state_shutdown     = systick_shutdown,
 80                 .set_state_oneshot      = systick_set_oneshot,
 81                 .event_handler          = systick_event_handler,
 82         },
 83 };
 84 
 85 static struct irqaction systick_irqaction = {
 86         .handler = systick_interrupt,
 87         .flags = IRQF_PERCPU | IRQF_TIMER,
 88         .dev_id = &systick.dev,
 89 };
 90 
 91 static int systick_shutdown(struct clock_event_device *evt)
 92 {
 93         struct systick_device *sdev;
 94 
 95         sdev = container_of(evt, struct systick_device, dev);
 96 
 97         if (sdev->irq_requested)
 98                 free_irq(systick.dev.irq, &systick_irqaction);
 99         sdev->irq_requested = 0;
100         iowrite32(0, systick.membase + SYSTICK_CONFIG);
101 
102         return 0;
103 }
104 
105 static int systick_set_oneshot(struct clock_event_device *evt)
106 {
107         struct systick_device *sdev;
108 
109         sdev = container_of(evt, struct systick_device, dev);
110 
111         if (!sdev->irq_requested)
112                 setup_irq(systick.dev.irq, &systick_irqaction);
113         sdev->irq_requested = 1;
114         iowrite32(CFG_EXT_STK_EN | CFG_CNT_EN,
115                   systick.membase + SYSTICK_CONFIG);
116 
117         return 0;
118 }
119 
120 static int __init ralink_systick_init(struct device_node *np)
121 {
122         int ret;
123 
124         systick.membase = of_iomap(np, 0);
125         if (!systick.membase)
126                 return -ENXIO;
127 
128         systick_irqaction.name = np->name;
129         systick.dev.name = np->name;
130         clockevents_calc_mult_shift(&systick.dev, SYSTICK_FREQ, 60);
131         systick.dev.max_delta_ns = clockevent_delta2ns(0x7fff, &systick.dev);
132         systick.dev.max_delta_ticks = 0x7fff;
133         systick.dev.min_delta_ns = clockevent_delta2ns(0x3, &systick.dev);
134         systick.dev.min_delta_ticks = 0x3;
135         systick.dev.irq = irq_of_parse_and_map(np, 0);
136         if (!systick.dev.irq) {
137                 pr_err("%pOFn: request_irq failed", np);
138                 return -EINVAL;
139         }
140 
141         ret = clocksource_mmio_init(systick.membase + SYSTICK_COUNT, np->name,
142                                     SYSTICK_FREQ, 301, 16,
143                                     clocksource_mmio_readl_up);
144         if (ret)
145                 return ret;
146 
147         clockevents_register_device(&systick.dev);
148 
149         pr_info("%pOFn: running - mult: %d, shift: %d\n",
150                         np, systick.dev.mult, systick.dev.shift);
151 
152         return 0;
153 }
154 
155 TIMER_OF_DECLARE(systick, "ralink,cevt-systick", ralink_systick_init);
156 

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