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) 107 108 static struct asm9260_timer_priv { 109 void __iomem *base; 110 unsigned long ticks_per_jiffy; 111 } priv; 112 113 static 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 } 122 123 static 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 } 128 129 static int asm9260_timer_shutdown(struct clock_event_device *evt) 130 { 131 __asm9260_timer_shutdown(evt); 132 return 0; 133 } 134 135 static 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 } 144 145 static 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 } 158 159 static 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 }; 170 171 static 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 */ 187 static void __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 panic("%s: unable to map resource", np->name); 197 198 clk = of_clk_get(np, 0); 199 200 ret = clk_prepare_enable(clk); 201 if (ret) 202 panic("Failed to enable clk!\n"); 203 204 irq = irq_of_parse_and_map(np, 0); 205 ret = request_irq(irq, asm9260_timer_interrupt, IRQF_TIMER, 206 DRIVER_NAME, &event_dev); 207 if (ret) 208 panic("Failed to setup irq!\n"); 209 210 /* set all timers for count-up */ 211 writel_relaxed(BM_DIR_DEFAULT, priv.base + HW_DIR); 212 /* disable divider */ 213 writel_relaxed(BM_PR_DISABLE, priv.base + HW_PR); 214 /* make sure all timers use every rising PCLK edge. */ 215 writel_relaxed(BM_CTCR_DEFAULT, priv.base + HW_CTCR); 216 /* enable interrupt for TC0 and clean setting for all other lines */ 217 writel_relaxed(BM_MCR_INT_EN(0) , priv.base + HW_MCR); 218 219 rate = clk_get_rate(clk); 220 clocksource_mmio_init(priv.base + HW_TC1, DRIVER_NAME, rate, 221 200, 32, clocksource_mmio_readl_up); 222 223 /* Seems like we can't use counter without match register even if 224 * actions for MR are disabled. So, set MR to max value. */ 225 writel_relaxed(0xffffffff, priv.base + HW_MR1); 226 /* enable TC1 */ 227 writel_relaxed(BM_C1_EN, priv.base + HW_TCR + SET_REG); 228 229 priv.ticks_per_jiffy = DIV_ROUND_CLOSEST(rate, HZ); 230 event_dev.cpumask = cpumask_of(0); 231 clockevents_config_and_register(&event_dev, rate, 0x2c00, 0xfffffffe); 232 } 233 CLOCKSOURCE_OF_DECLARE(asm9260_timer, "alphascale,asm9260-timer", 234 asm9260_timer_init); 235