1/*
2 * Copyright (C) 2014 Oleksij Rempel <linux@rempel-privat.de>
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version 2
7 * of the License, or (at your option) any later version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/init.h>
12#include <linux/interrupt.h>
13#include <linux/sched.h>
14#include <linux/clk.h>
15#include <linux/clocksource.h>
16#include <linux/clockchips.h>
17#include <linux/io.h>
18#include <linux/of.h>
19#include <linux/of_address.h>
20#include <linux/of_irq.h>
21#include <linux/bitops.h>
22
23#define DRIVER_NAME "asm9260-timer"
24
25/*
26 * this device provide 4 offsets for each register:
27 * 0x0 - plain read write mode
28 * 0x4 - set mode, OR logic.
29 * 0x8 - clr mode, XOR logic.
30 * 0xc - togle mode.
31 */
32#define SET_REG 4
33#define CLR_REG 8
34
35#define HW_IR 0x0000 /* RW. Interrupt */
36#define BM_IR_CR0 BIT(4)
37#define BM_IR_MR3 BIT(3)
38#define BM_IR_MR2 BIT(2)
39#define BM_IR_MR1 BIT(1)
40#define BM_IR_MR0 BIT(0)
41
42#define HW_TCR 0x0010 /* RW. Timer controller */
43/* BM_C*_RST
44 * Timer Counter and the Prescale Counter are synchronously reset on the
45 * next positive edge of PCLK. The counters remain reset until TCR[1] is
46 * returned to zero. */
47#define BM_C3_RST BIT(7)
48#define BM_C2_RST BIT(6)
49#define BM_C1_RST BIT(5)
50#define BM_C0_RST BIT(4)
51/* BM_C*_EN
52 * 1 - Timer Counter and Prescale Counter are enabled for counting
53 * 0 - counters are disabled */
54#define BM_C3_EN BIT(3)
55#define BM_C2_EN BIT(2)
56#define BM_C1_EN BIT(1)
57#define BM_C0_EN BIT(0)
58
59#define HW_DIR 0x0020 /* RW. Direction? */
60/* 00 - count up
61 * 01 - count down
62 * 10 - ?? 2^n/2 */
63#define BM_DIR_COUNT_UP 0
64#define BM_DIR_COUNT_DOWN 1
65#define BM_DIR0_SHIFT 0
66#define BM_DIR1_SHIFT 4
67#define BM_DIR2_SHIFT 8
68#define BM_DIR3_SHIFT 12
69#define BM_DIR_DEFAULT (BM_DIR_COUNT_UP << BM_DIR0_SHIFT | \
70 BM_DIR_COUNT_UP << BM_DIR1_SHIFT | \
71 BM_DIR_COUNT_UP << BM_DIR2_SHIFT | \
72 BM_DIR_COUNT_UP << BM_DIR3_SHIFT)
73
74#define HW_TC0 0x0030 /* RO. Timer counter 0 */
75/* HW_TC*. Timer counter owerflow (0xffff.ffff to 0x0000.0000) do not generate
76 * interrupt. This registers can be used to detect overflow */
77#define HW_TC1 0x0040
78#define HW_TC2 0x0050
79#define HW_TC3 0x0060
80
81#define HW_PR 0x0070 /* RW. prescaler */
82#define BM_PR_DISABLE 0
83#define HW_PC 0x0080 /* RO. Prescaler counter */
84#define HW_MCR 0x0090 /* RW. Match control */
85/* enable interrupt on match */
86#define BM_MCR_INT_EN(n) (1 << (n * 3 + 0))
87/* enable TC reset on match */
88#define BM_MCR_RES_EN(n) (1 << (n * 3 + 1))
89/* enable stop TC on match */
90#define BM_MCR_STOP_EN(n) (1 << (n * 3 + 2))
91
92#define HW_MR0 0x00a0 /* RW. Match reg */
93#define HW_MR1 0x00b0
94#define HW_MR2 0x00C0
95#define HW_MR3 0x00D0
96
97#define HW_CTCR 0x0180 /* Counter control */
98#define BM_CTCR0_SHIFT 0
99#define BM_CTCR1_SHIFT 2
100#define BM_CTCR2_SHIFT 4
101#define BM_CTCR3_SHIFT 6
102#define BM_CTCR_TM 0 /* Timer mode. Every rising PCLK edge. */
103#define BM_CTCR_DEFAULT (BM_CTCR_TM << BM_CTCR0_SHIFT | \
104 BM_CTCR_TM << BM_CTCR1_SHIFT | \
105 BM_CTCR_TM << BM_CTCR2_SHIFT | \
106 BM_CTCR_TM << BM_CTCR3_SHIFT)
107
108static struct asm9260_timer_priv {
109 void __iomem *base;
110 unsigned long ticks_per_jiffy;
111} priv;
112
113static int asm9260_timer_set_next_event(unsigned long delta,
114 struct clock_event_device *evt)
115{
116 /* configure match count for TC0 */
117 writel_relaxed(delta, priv.base + HW_MR0);
118 /* enable TC0 */
119 writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
120 return 0;
121}
122
123static inline void __asm9260_timer_shutdown(struct clock_event_device *evt)
124{
125 /* stop timer0 */
126 writel_relaxed(BM_C0_EN, priv.base + HW_TCR + CLR_REG);
127}
128
129static int asm9260_timer_shutdown(struct clock_event_device *evt)
130{
131 __asm9260_timer_shutdown(evt);
132 return 0;
133}
134
135static int asm9260_timer_set_oneshot(struct clock_event_device *evt)
136{
137 __asm9260_timer_shutdown(evt);
138
139 /* enable reset and stop on match */
140 writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
141 priv.base + HW_MCR + SET_REG);
142 return 0;
143}
144
145static int asm9260_timer_set_periodic(struct clock_event_device *evt)
146{
147 __asm9260_timer_shutdown(evt);
148
149 /* disable reset and stop on match */
150 writel_relaxed(BM_MCR_RES_EN(0) | BM_MCR_STOP_EN(0),
151 priv.base + HW_MCR + CLR_REG);
152 /* configure match count for TC0 */
153 writel_relaxed(priv.ticks_per_jiffy, priv.base + HW_MR0);
154 /* enable TC0 */
155 writel_relaxed(BM_C0_EN, priv.base + HW_TCR + SET_REG);
156 return 0;
157}
158
159static struct clock_event_device event_dev = {
160 .name = DRIVER_NAME,
161 .rating = 200,
162 .features = CLOCK_EVT_FEAT_PERIODIC |
163 CLOCK_EVT_FEAT_ONESHOT,
164 .set_next_event = asm9260_timer_set_next_event,
165 .set_state_shutdown = asm9260_timer_shutdown,
166 .set_state_periodic = asm9260_timer_set_periodic,
167 .set_state_oneshot = asm9260_timer_set_oneshot,
168 .tick_resume = asm9260_timer_shutdown,
169};
170
171static irqreturn_t asm9260_timer_interrupt(int irq, void *dev_id)
172{
173 struct clock_event_device *evt = dev_id;
174
175 evt->event_handler(evt);
176
177 writel_relaxed(BM_IR_MR0, priv.base + HW_IR);
178
179 return IRQ_HANDLED;
180}
181
182/*
183 * ---------------------------------------------------------------------------
184 * Timer initialization
185 * ---------------------------------------------------------------------------
186 */
187static int __init asm9260_timer_init(struct device_node *np)
188{
189 int irq;
190 struct clk *clk;
191 int ret;
192 unsigned long rate;
193
194 priv.base = of_io_request_and_map(np, 0, np->name);
195 if (IS_ERR(priv.base)) {
196 pr_err("%pOFn: unable to map resource\n", np);
197 return PTR_ERR(priv.base);
198 }
199
200 clk = of_clk_get(np, 0);
201
202 ret = clk_prepare_enable(clk);
203 if (ret) {
204 pr_err("Failed to enable clk!\n");
205 return ret;
206 }
207
208 irq = irq_of_parse_and_map(np, 0);
209 ret = request_irq(irq, asm9260_timer_interrupt, IRQF_TIMER,
210 DRIVER_NAME, &event_dev);
211 if (ret) {
212 pr_err("Failed to setup irq!\n");
213 return ret;
214 }
215
216 /* set all timers for count-up */
217 writel_relaxed(BM_DIR_DEFAULT, priv.base + HW_DIR);
218 /* disable divider */
219 writel_relaxed(BM_PR_DISABLE, priv.base + HW_PR);
220 /* make sure all timers use every rising PCLK edge. */
221 writel_relaxed(BM_CTCR_DEFAULT, priv.base + HW_CTCR);
222 /* enable interrupt for TC0 and clean setting for all other lines */
223 writel_relaxed(BM_MCR_INT_EN(0) , priv.base + HW_MCR);
224
225 rate = clk_get_rate(clk);
226 clocksource_mmio_init(priv.base + HW_TC1, DRIVER_NAME, rate,
227 200, 32, clocksource_mmio_readl_up);
228
229 /* Seems like we can't use counter without match register even if
230 * actions for MR are disabled. So, set MR to max value. */
231 writel_relaxed(0xffffffff, priv.base + HW_MR1);
232 /* enable TC1 */
233 writel_relaxed(BM_C1_EN, priv.base + HW_TCR + SET_REG);
234
235 priv.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ);
236 event_dev.cpumask = cpumask_of(0);
237 clockevents_config_and_register(&event_dev, rate, 0x2c00, 0xfffffffe);
238
239 return 0;
240}
241TIMER_OF_DECLARE(asm9260_timer, "alphascale,asm9260-timer",
242 asm9260_timer_init);
243