1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * H8/300 16bit Timer driver
4 *
5 * Copyright 2015 Yoshinori Sato <ysato@users.sourcefoge.jp>
6 */
7
8 #include <linux/interrupt.h>
9 #include <linux/init.h>
10 #include <linux/clocksource.h>
11 #include <linux/clk.h>
12 #include <linux/io.h>
13 #include <linux/of.h>
14 #include <linux/of_address.h>
15 #include <linux/of_irq.h>
16
17 #define TSTR 0
18 #define TISRC 6
19
20 #define TCR 0
21 #define TCNT 2
22
23 #define bset(b, a) iowrite8(ioread8(a) | (1 << (b)), (a))
24 #define bclr(b, a) iowrite8(ioread8(a) & ~(1 << (b)), (a))
25
26 struct timer16_priv {
27 struct clocksource cs;
28 unsigned long total_cycles;
29 void __iomem *mapbase;
30 void __iomem *mapcommon;
31 unsigned short cs_enabled;
32 unsigned char enb;
33 unsigned char ovf;
34 unsigned char ovie;
35 };
36
timer16_get_counter(struct timer16_priv * p)37 static unsigned long timer16_get_counter(struct timer16_priv *p)
38 {
39 unsigned short v1, v2, v3;
40 unsigned char o1, o2;
41
42 o1 = ioread8(p->mapcommon + TISRC) & p->ovf;
43
44 /* Make sure the timer value is stable. Stolen from acpi_pm.c */
45 do {
46 o2 = o1;
47 v1 = ioread16be(p->mapbase + TCNT);
48 v2 = ioread16be(p->mapbase + TCNT);
49 v3 = ioread16be(p->mapbase + TCNT);
50 o1 = ioread8(p->mapcommon + TISRC) & p->ovf;
51 } while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3)
52 || (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2)));
53
54 if (likely(!o1))
55 return v2;
56 else
57 return v2 + 0x10000;
58 }
59
60
timer16_interrupt(int irq,void * dev_id)61 static irqreturn_t timer16_interrupt(int irq, void *dev_id)
62 {
63 struct timer16_priv *p = (struct timer16_priv *)dev_id;
64
65 bclr(p->ovf, p->mapcommon + TISRC);
66 p->total_cycles += 0x10000;
67
68 return IRQ_HANDLED;
69 }
70
cs_to_priv(struct clocksource * cs)71 static inline struct timer16_priv *cs_to_priv(struct clocksource *cs)
72 {
73 return container_of(cs, struct timer16_priv, cs);
74 }
75
timer16_clocksource_read(struct clocksource * cs)76 static u64 timer16_clocksource_read(struct clocksource *cs)
77 {
78 struct timer16_priv *p = cs_to_priv(cs);
79 unsigned long raw, value;
80
81 value = p->total_cycles;
82 raw = timer16_get_counter(p);
83
84 return value + raw;
85 }
86
timer16_enable(struct clocksource * cs)87 static int timer16_enable(struct clocksource *cs)
88 {
89 struct timer16_priv *p = cs_to_priv(cs);
90
91 WARN_ON(p->cs_enabled);
92
93 p->total_cycles = 0;
94 iowrite16be(0x0000, p->mapbase + TCNT);
95 iowrite8(0x83, p->mapbase + TCR);
96 bset(p->ovie, p->mapcommon + TISRC);
97 bset(p->enb, p->mapcommon + TSTR);
98
99 p->cs_enabled = true;
100 return 0;
101 }
102
timer16_disable(struct clocksource * cs)103 static void timer16_disable(struct clocksource *cs)
104 {
105 struct timer16_priv *p = cs_to_priv(cs);
106
107 WARN_ON(!p->cs_enabled);
108
109 bclr(p->ovie, p->mapcommon + TISRC);
110 bclr(p->enb, p->mapcommon + TSTR);
111
112 p->cs_enabled = false;
113 }
114
115 static struct timer16_priv timer16_priv = {
116 .cs = {
117 .name = "h8300_16timer",
118 .rating = 200,
119 .read = timer16_clocksource_read,
120 .enable = timer16_enable,
121 .disable = timer16_disable,
122 .mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8),
123 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
124 },
125 };
126
127 #define REG_CH 0
128 #define REG_COMM 1
129
h8300_16timer_init(struct device_node * node)130 static int __init h8300_16timer_init(struct device_node *node)
131 {
132 void __iomem *base[2];
133 int ret, irq;
134 unsigned int ch;
135 struct clk *clk;
136
137 clk = of_clk_get(node, 0);
138 if (IS_ERR(clk)) {
139 pr_err("failed to get clock for clocksource\n");
140 return PTR_ERR(clk);
141 }
142
143 ret = -ENXIO;
144 base[REG_CH] = of_iomap(node, 0);
145 if (!base[REG_CH]) {
146 pr_err("failed to map registers for clocksource\n");
147 goto free_clk;
148 }
149
150 base[REG_COMM] = of_iomap(node, 1);
151 if (!base[REG_COMM]) {
152 pr_err("failed to map registers for clocksource\n");
153 goto unmap_ch;
154 }
155
156 ret = -EINVAL;
157 irq = irq_of_parse_and_map(node, 0);
158 if (!irq) {
159 pr_err("failed to get irq for clockevent\n");
160 goto unmap_comm;
161 }
162
163 of_property_read_u32(node, "renesas,channel", &ch);
164
165 timer16_priv.mapbase = base[REG_CH];
166 timer16_priv.mapcommon = base[REG_COMM];
167 timer16_priv.enb = ch;
168 timer16_priv.ovf = ch;
169 timer16_priv.ovie = 4 + ch;
170
171 ret = request_irq(irq, timer16_interrupt,
172 IRQF_TIMER, timer16_priv.cs.name, &timer16_priv);
173 if (ret < 0) {
174 pr_err("failed to request irq %d of clocksource\n", irq);
175 goto unmap_comm;
176 }
177
178 clocksource_register_hz(&timer16_priv.cs,
179 clk_get_rate(clk) / 8);
180 return 0;
181
182 unmap_comm:
183 iounmap(base[REG_COMM]);
184 unmap_ch:
185 iounmap(base[REG_CH]);
186 free_clk:
187 clk_put(clk);
188 return ret;
189 }
190
191 TIMER_OF_DECLARE(h8300_16bit, "renesas,16bit-timer",
192 h8300_16timer_init);
193