1/*
2 * Conexant Digicolor timer driver
3 *
4 * Author: Baruch Siach <baruch@tkos.co.il>
5 *
6 * Copyright (C) 2014 Paradox Innovation Ltd.
7 *
8 * Based on:
9 * Allwinner SoCs hstimer driver
10 *
11 * Copyright (C) 2013 Maxime Ripard
12 *
13 * Maxime Ripard <maxime.ripard@free-electrons.com>
14 *
15 * This file is licensed under the terms of the GNU General Public
16 * License version 2. This program is licensed "as is" without any
17 * warranty of any kind, whether express or implied.
18 */
19
20/*
21 * Conexant Digicolor SoCs have 8 configurable timers, named from "Timer A" to
22 * "Timer H". Timer A is the only one with watchdog support, so it is dedicated
23 * to the watchdog driver. This driver uses Timer B for sched_clock(), and
24 * Timer C for clockevents.
25 */
26
27#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
28
29#include <linux/clk.h>
30#include <linux/clockchips.h>
31#include <linux/interrupt.h>
32#include <linux/irq.h>
33#include <linux/irqreturn.h>
34#include <linux/sched/clock.h>
35#include <linux/sched_clock.h>
36#include <linux/of.h>
37#include <linux/of_address.h>
38#include <linux/of_irq.h>
39
40enum {
41 TIMER_A,
42 TIMER_B,
43 TIMER_C,
44 TIMER_D,
45 TIMER_E,
46 TIMER_F,
47 TIMER_G,
48 TIMER_H,
49};
50
51#define CONTROL(t) ((t)*8)
52#define COUNT(t) ((t)*8 + 4)
53
54#define CONTROL_DISABLE 0
55#define CONTROL_ENABLE BIT(0)
56#define CONTROL_MODE(m) ((m) << 4)
57#define CONTROL_MODE_ONESHOT CONTROL_MODE(1)
58#define CONTROL_MODE_PERIODIC CONTROL_MODE(2)
59
60struct digicolor_timer {
61 struct clock_event_device ce;
62 void __iomem *base;
63 u32 ticks_per_jiffy;
64 int timer_id; /* one of TIMER_* */
65};
66
67static struct digicolor_timer *dc_timer(struct clock_event_device *ce)
68{
69 return container_of(ce, struct digicolor_timer, ce);
70}
71
72static inline void dc_timer_disable(struct clock_event_device *ce)
73{
74 struct digicolor_timer *dt = dc_timer(ce);
75 writeb(CONTROL_DISABLE, dt->base + CONTROL(dt->timer_id));
76}
77
78static inline void dc_timer_enable(struct clock_event_device *ce, u32 mode)
79{
80 struct digicolor_timer *dt = dc_timer(ce);
81 writeb(CONTROL_ENABLE | mode, dt->base + CONTROL(dt->timer_id));
82}
83
84static inline void dc_timer_set_count(struct clock_event_device *ce,
85 unsigned long count)
86{
87 struct digicolor_timer *dt = dc_timer(ce);
88 writel(count, dt->base + COUNT(dt->timer_id));
89}
90
91static int digicolor_clkevt_shutdown(struct clock_event_device *ce)
92{
93 dc_timer_disable(ce);
94 return 0;
95}
96
97static int digicolor_clkevt_set_oneshot(struct clock_event_device *ce)
98{
99 dc_timer_disable(ce);
100 dc_timer_enable(ce, CONTROL_MODE_ONESHOT);
101 return 0;
102}
103
104static int digicolor_clkevt_set_periodic(struct clock_event_device *ce)
105{
106 struct digicolor_timer *dt = dc_timer(ce);
107
108 dc_timer_disable(ce);
109 dc_timer_set_count(ce, dt->ticks_per_jiffy);
110 dc_timer_enable(ce, CONTROL_MODE_PERIODIC);
111 return 0;
112}
113
114static int digicolor_clkevt_next_event(unsigned long evt,
115 struct clock_event_device *ce)
116{
117 dc_timer_disable(ce);
118 dc_timer_set_count(ce, evt);
119 dc_timer_enable(ce, CONTROL_MODE_ONESHOT);
120
121 return 0;
122}
123
124static struct digicolor_timer dc_timer_dev = {
125 .ce = {
126 .name = "digicolor_tick",
127 .rating = 340,
128 .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
129 .set_state_shutdown = digicolor_clkevt_shutdown,
130 .set_state_periodic = digicolor_clkevt_set_periodic,
131 .set_state_oneshot = digicolor_clkevt_set_oneshot,
132 .tick_resume = digicolor_clkevt_shutdown,
133 .set_next_event = digicolor_clkevt_next_event,
134 },
135 .timer_id = TIMER_C,
136};
137
138static irqreturn_t digicolor_timer_interrupt(int irq, void *dev_id)
139{
140 struct clock_event_device *evt = dev_id;
141
142 evt->event_handler(evt);
143
144 return IRQ_HANDLED;
145}
146
147static u64 notrace digicolor_timer_sched_read(void)
148{
149 return ~readl(dc_timer_dev.base + COUNT(TIMER_B));
150}
151
152static int __init digicolor_timer_init(struct device_node *node)
153{
154 unsigned long rate;
155 struct clk *clk;
156 int ret, irq;
157
158 /*
159 * timer registers are shared with the watchdog timer;
160 * don't map exclusively
161 */
162 dc_timer_dev.base = of_iomap(node, 0);
163 if (!dc_timer_dev.base) {
164 pr_err("Can't map registers\n");
165 return -ENXIO;
166 }
167
168 irq = irq_of_parse_and_map(node, dc_timer_dev.timer_id);
169 if (irq <= 0) {
170 pr_err("Can't parse IRQ\n");
171 return -EINVAL;
172 }
173
174 clk = of_clk_get(node, 0);
175 if (IS_ERR(clk)) {
176 pr_err("Can't get timer clock\n");
177 return PTR_ERR(clk);
178 }
179 clk_prepare_enable(clk);
180 rate = clk_get_rate(clk);
181 dc_timer_dev.ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
182
183 writeb(CONTROL_DISABLE, dc_timer_dev.base + CONTROL(TIMER_B));
184 writel(UINT_MAX, dc_timer_dev.base + COUNT(TIMER_B));
185 writeb(CONTROL_ENABLE, dc_timer_dev.base + CONTROL(TIMER_B));
186
187 sched_clock_register(digicolor_timer_sched_read, 32, rate);
188 clocksource_mmio_init(dc_timer_dev.base + COUNT(TIMER_B), node->name,
189 rate, 340, 32, clocksource_mmio_readl_down);
190
191 ret = request_irq(irq, digicolor_timer_interrupt,
192 IRQF_TIMER | IRQF_IRQPOLL, "digicolor_timerC",
193 &dc_timer_dev.ce);
194 if (ret) {
195 pr_warn("request of timer irq %d failed (%d)\n", irq, ret);
196 return ret;
197 }
198
199 dc_timer_dev.ce.cpumask = cpu_possible_mask;
200 dc_timer_dev.ce.irq = irq;
201
202 clockevents_config_and_register(&dc_timer_dev.ce, rate, 0, 0xffffffff);
203
204 return 0;
205}
206TIMER_OF_DECLARE(conexant_digicolor, "cnxt,cx92755-timer",
207 digicolor_timer_init);
208