1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Renesas Timer Support - OSTM
4 *
5 * Copyright (C) 2017 Renesas Electronics America, Inc.
6 * Copyright (C) 2017 Chris Brandt
7 */
8
9#include <linux/of_address.h>
10#include <linux/of_irq.h>
11#include <linux/clk.h>
12#include <linux/clockchips.h>
13#include <linux/interrupt.h>
14#include <linux/sched_clock.h>
15#include <linux/slab.h>
16
17/*
18 * The OSTM contains independent channels.
19 * The first OSTM channel probed will be set up as a free running
20 * clocksource. Additionally we will use this clocksource for the system
21 * schedule timer sched_clock().
22 *
23 * The second (or more) channel probed will be set up as an interrupt
24 * driven clock event.
25 */
26
27struct ostm_device {
28 void __iomem *base;
29 unsigned long ticks_per_jiffy;
30 struct clock_event_device ced;
31};
32
33static void __iomem *system_clock; /* For sched_clock() */
34
35/* OSTM REGISTERS */
36#define OSTM_CMP 0x000 /* RW,32 */
37#define OSTM_CNT 0x004 /* R,32 */
38#define OSTM_TE 0x010 /* R,8 */
39#define OSTM_TS 0x014 /* W,8 */
40#define OSTM_TT 0x018 /* W,8 */
41#define OSTM_CTL 0x020 /* RW,8 */
42
43#define TE 0x01
44#define TS 0x01
45#define TT 0x01
46#define CTL_PERIODIC 0x00
47#define CTL_ONESHOT 0x02
48#define CTL_FREERUN 0x02
49
50static struct ostm_device *ced_to_ostm(struct clock_event_device *ced)
51{
52 return container_of(ced, struct ostm_device, ced);
53}
54
55static void ostm_timer_stop(struct ostm_device *ostm)
56{
57 if (readb(ostm->base + OSTM_TE) & TE) {
58 writeb(TT, ostm->base + OSTM_TT);
59
60 /*
61 * Read back the register simply to confirm the write operation
62 * has completed since I/O writes can sometimes get queued by
63 * the bus architecture.
64 */
65 while (readb(ostm->base + OSTM_TE) & TE)
66 ;
67 }
68}
69
70static int __init ostm_init_clksrc(struct ostm_device *ostm, unsigned long rate)
71{
72 /*
73 * irq not used (clock sources don't use interrupts)
74 */
75
76 ostm_timer_stop(ostm);
77
78 writel(0, ostm->base + OSTM_CMP);
79 writeb(CTL_FREERUN, ostm->base + OSTM_CTL);
80 writeb(TS, ostm->base + OSTM_TS);
81
82 return clocksource_mmio_init(ostm->base + OSTM_CNT,
83 "ostm", rate,
84 300, 32, clocksource_mmio_readl_up);
85}
86
87static u64 notrace ostm_read_sched_clock(void)
88{
89 return readl(system_clock);
90}
91
92static void __init ostm_init_sched_clock(struct ostm_device *ostm,
93 unsigned long rate)
94{
95 system_clock = ostm->base + OSTM_CNT;
96 sched_clock_register(ostm_read_sched_clock, 32, rate);
97}
98
99static int ostm_clock_event_next(unsigned long delta,
100 struct clock_event_device *ced)
101{
102 struct ostm_device *ostm = ced_to_ostm(ced);
103
104 ostm_timer_stop(ostm);
105
106 writel(delta, ostm->base + OSTM_CMP);
107 writeb(CTL_ONESHOT, ostm->base + OSTM_CTL);
108 writeb(TS, ostm->base + OSTM_TS);
109
110 return 0;
111}
112
113static int ostm_shutdown(struct clock_event_device *ced)
114{
115 struct ostm_device *ostm = ced_to_ostm(ced);
116
117 ostm_timer_stop(ostm);
118
119 return 0;
120}
121static int ostm_set_periodic(struct clock_event_device *ced)
122{
123 struct ostm_device *ostm = ced_to_ostm(ced);
124
125 if (clockevent_state_oneshot(ced) || clockevent_state_periodic(ced))
126 ostm_timer_stop(ostm);
127
128 writel(ostm->ticks_per_jiffy - 1, ostm->base + OSTM_CMP);
129 writeb(CTL_PERIODIC, ostm->base + OSTM_CTL);
130 writeb(TS, ostm->base + OSTM_TS);
131
132 return 0;
133}
134
135static int ostm_set_oneshot(struct clock_event_device *ced)
136{
137 struct ostm_device *ostm = ced_to_ostm(ced);
138
139 ostm_timer_stop(ostm);
140
141 return 0;
142}
143
144static irqreturn_t ostm_timer_interrupt(int irq, void *dev_id)
145{
146 struct ostm_device *ostm = dev_id;
147
148 if (clockevent_state_oneshot(&ostm->ced))
149 ostm_timer_stop(ostm);
150
151 /* notify clockevent layer */
152 if (ostm->ced.event_handler)
153 ostm->ced.event_handler(&ostm->ced);
154
155 return IRQ_HANDLED;
156}
157
158static int __init ostm_init_clkevt(struct ostm_device *ostm, int irq,
159 unsigned long rate)
160{
161 struct clock_event_device *ced = &ostm->ced;
162 int ret = -ENXIO;
163
164 ret = request_irq(irq, ostm_timer_interrupt,
165 IRQF_TIMER | IRQF_IRQPOLL,
166 "ostm", ostm);
167 if (ret) {
168 pr_err("ostm: failed to request irq\n");
169 return ret;
170 }
171
172 ced->name = "ostm";
173 ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC;
174 ced->set_state_shutdown = ostm_shutdown;
175 ced->set_state_periodic = ostm_set_periodic;
176 ced->set_state_oneshot = ostm_set_oneshot;
177 ced->set_next_event = ostm_clock_event_next;
178 ced->shift = 32;
179 ced->rating = 300;
180 ced->cpumask = cpumask_of(0);
181 clockevents_config_and_register(ced, rate, 0xf, 0xffffffff);
182
183 return 0;
184}
185
186static int __init ostm_init(struct device_node *np)
187{
188 struct ostm_device *ostm;
189 int ret = -EFAULT;
190 struct clk *ostm_clk = NULL;
191 int irq;
192 unsigned long rate;
193
194 ostm = kzalloc(sizeof(*ostm), GFP_KERNEL);
195 if (!ostm)
196 return -ENOMEM;
197
198 ostm->base = of_iomap(np, 0);
199 if (!ostm->base) {
200 pr_err("ostm: failed to remap I/O memory\n");
201 goto err;
202 }
203
204 irq = irq_of_parse_and_map(np, 0);
205 if (irq < 0) {
206 pr_err("ostm: Failed to get irq\n");
207 goto err;
208 }
209
210 ostm_clk = of_clk_get(np, 0);
211 if (IS_ERR(ostm_clk)) {
212 pr_err("ostm: Failed to get clock\n");
213 ostm_clk = NULL;
214 goto err;
215 }
216
217 ret = clk_prepare_enable(ostm_clk);
218 if (ret) {
219 pr_err("ostm: Failed to enable clock\n");
220 goto err;
221 }
222
223 rate = clk_get_rate(ostm_clk);
224 ostm->ticks_per_jiffy = (rate + HZ / 2) / HZ;
225
226 /*
227 * First probed device will be used as system clocksource. Any
228 * additional devices will be used as clock events.
229 */
230 if (!system_clock) {
231 ret = ostm_init_clksrc(ostm, rate);
232
233 if (!ret) {
234 ostm_init_sched_clock(ostm, rate);
235 pr_info("ostm: used for clocksource\n");
236 }
237
238 } else {
239 ret = ostm_init_clkevt(ostm, irq, rate);
240
241 if (!ret)
242 pr_info("ostm: used for clock events\n");
243 }
244
245err:
246 if (ret) {
247 clk_disable_unprepare(ostm_clk);
248 iounmap(ostm->base);
249 kfree(ostm);
250 return ret;
251 }
252
253 return 0;
254}
255
256TIMER_OF_DECLARE(ostm, "renesas,ostm", ostm_init);
257