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15#include <linux/kernel.h>
16#include <linux/irq.h>
17#include <linux/interrupt.h>
18#include <linux/module.h>
19#include <linux/cs5535.h>
20#include <linux/clockchips.h>
21
22#define DRV_NAME "cs5535-clockevt"
23
24static int timer_irq;
25module_param_named(irq, timer_irq, int, 0644);
26MODULE_PARM_DESC(irq, "Which IRQ to use for the clock source MFGPT ticks.");
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44
45static unsigned int cs5535_tick_mode = CLOCK_EVT_MODE_SHUTDOWN;
46static struct cs5535_mfgpt_timer *cs5535_event_clock;
47
48
49
50#define MFGPT_DIVISOR 16
51#define MFGPT_SCALE 4
52#define MFGPT_HZ (32768 / MFGPT_DIVISOR)
53#define MFGPT_PERIODIC (MFGPT_HZ / HZ)
54
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61
62
63static void disable_timer(struct cs5535_mfgpt_timer *timer)
64{
65
66 cs5535_mfgpt_write(timer, MFGPT_REG_SETUP,
67 (uint16_t) ~MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP1 |
68 MFGPT_SETUP_CMP2);
69}
70
71static void start_timer(struct cs5535_mfgpt_timer *timer, uint16_t delta)
72{
73 cs5535_mfgpt_write(timer, MFGPT_REG_CMP2, delta);
74 cs5535_mfgpt_write(timer, MFGPT_REG_COUNTER, 0);
75
76 cs5535_mfgpt_write(timer, MFGPT_REG_SETUP,
77 MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
78}
79
80static void mfgpt_set_mode(enum clock_event_mode mode,
81 struct clock_event_device *evt)
82{
83 disable_timer(cs5535_event_clock);
84
85 if (mode == CLOCK_EVT_MODE_PERIODIC)
86 start_timer(cs5535_event_clock, MFGPT_PERIODIC);
87
88 cs5535_tick_mode = mode;
89}
90
91static int mfgpt_next_event(unsigned long delta, struct clock_event_device *evt)
92{
93 start_timer(cs5535_event_clock, delta);
94 return 0;
95}
96
97static struct clock_event_device cs5535_clockevent = {
98 .name = DRV_NAME,
99 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
100 .set_mode = mfgpt_set_mode,
101 .set_next_event = mfgpt_next_event,
102 .rating = 250,
103 .shift = 32
104};
105
106static irqreturn_t mfgpt_tick(int irq, void *dev_id)
107{
108 uint16_t val = cs5535_mfgpt_read(cs5535_event_clock, MFGPT_REG_SETUP);
109
110
111 if (!(val & (MFGPT_SETUP_SETUP | MFGPT_SETUP_CMP2 | MFGPT_SETUP_CMP1)))
112 return IRQ_NONE;
113
114
115 disable_timer(cs5535_event_clock);
116
117 if (cs5535_tick_mode == CLOCK_EVT_MODE_SHUTDOWN)
118 return IRQ_HANDLED;
119
120
121 cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_COUNTER, 0);
122
123
124
125 if (cs5535_tick_mode == CLOCK_EVT_MODE_PERIODIC)
126 cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP,
127 MFGPT_SETUP_CNTEN | MFGPT_SETUP_CMP2);
128
129 cs5535_clockevent.event_handler(&cs5535_clockevent);
130 return IRQ_HANDLED;
131}
132
133static struct irqaction mfgptirq = {
134 .handler = mfgpt_tick,
135 .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_TIMER | IRQF_SHARED,
136 .name = DRV_NAME,
137};
138
139static int __init cs5535_mfgpt_init(void)
140{
141 struct cs5535_mfgpt_timer *timer;
142 int ret;
143 uint16_t val;
144
145 timer = cs5535_mfgpt_alloc_timer(MFGPT_TIMER_ANY, MFGPT_DOMAIN_WORKING);
146 if (!timer) {
147 printk(KERN_ERR DRV_NAME ": Could not allocate MFGPT timer\n");
148 return -ENODEV;
149 }
150 cs5535_event_clock = timer;
151
152
153 if (cs5535_mfgpt_setup_irq(timer, MFGPT_CMP2, &timer_irq)) {
154 printk(KERN_ERR DRV_NAME ": Could not set up IRQ %d\n",
155 timer_irq);
156 goto err_timer;
157 }
158
159
160 ret = setup_irq(timer_irq, &mfgptirq);
161 if (ret) {
162 printk(KERN_ERR DRV_NAME ": Unable to set up the interrupt.\n");
163 goto err_irq;
164 }
165
166
167 val = MFGPT_SCALE | (3 << 8);
168
169 cs5535_mfgpt_write(cs5535_event_clock, MFGPT_REG_SETUP, val);
170
171
172 cs5535_clockevent.mult = div_sc(MFGPT_HZ, NSEC_PER_SEC,
173 cs5535_clockevent.shift);
174 cs5535_clockevent.min_delta_ns = clockevent_delta2ns(0xF,
175 &cs5535_clockevent);
176 cs5535_clockevent.max_delta_ns = clockevent_delta2ns(0xFFFE,
177 &cs5535_clockevent);
178
179 printk(KERN_INFO DRV_NAME
180 ": Registering MFGPT timer as a clock event, using IRQ %d\n",
181 timer_irq);
182 clockevents_register_device(&cs5535_clockevent);
183
184 return 0;
185
186err_irq:
187 cs5535_mfgpt_release_irq(cs5535_event_clock, MFGPT_CMP2, &timer_irq);
188err_timer:
189 cs5535_mfgpt_free_timer(cs5535_event_clock);
190 printk(KERN_ERR DRV_NAME ": Unable to set up the MFGPT clock source\n");
191 return -EIO;
192}
193
194module_init(cs5535_mfgpt_init);
195
196MODULE_AUTHOR("Andres Salomon <dilinger@queued.net>");
197MODULE_DESCRIPTION("CS5535/CS5536 MFGPT clock event driver");
198MODULE_LICENSE("GPL");
199