1 /* 2 * Copyright (C) 2008 STMicroelectronics 3 * Copyright (C) 2010 Alessandro Rubini 4 * Copyright (C) 2010 Linus Walleij for ST-Ericsson 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2, as 8 * published by the Free Software Foundation. 9 */ 10 #include <linux/init.h> 11 #include <linux/interrupt.h> 12 #include <linux/irq.h> 13 #include <linux/io.h> 14 #include <linux/clockchips.h> 15 #include <linux/clocksource.h> 16 #include <linux/of_address.h> 17 #include <linux/of_irq.h> 18 #include <linux/of_platform.h> 19 #include <linux/clk.h> 20 #include <linux/jiffies.h> 21 #include <linux/delay.h> 22 #include <linux/err.h> 23 #include <linux/sched_clock.h> 24 #include <asm/mach/time.h> 25 26 /* 27 * The MTU device hosts four different counters, with 4 set of 28 * registers. These are register names. 29 */ 30 31 #define MTU_IMSC 0x00 /* Interrupt mask set/clear */ 32 #define MTU_RIS 0x04 /* Raw interrupt status */ 33 #define MTU_MIS 0x08 /* Masked interrupt status */ 34 #define MTU_ICR 0x0C /* Interrupt clear register */ 35 36 /* per-timer registers take 0..3 as argument */ 37 #define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */ 38 #define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */ 39 #define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */ 40 #define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */ 41 42 /* bits for the control register */ 43 #define MTU_CRn_ENA 0x80 44 #define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */ 45 #define MTU_CRn_PRESCALE_MASK 0x0c 46 #define MTU_CRn_PRESCALE_1 0x00 47 #define MTU_CRn_PRESCALE_16 0x04 48 #define MTU_CRn_PRESCALE_256 0x08 49 #define MTU_CRn_32BITS 0x02 50 #define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/ 51 52 /* Other registers are usual amba/primecell registers, currently not used */ 53 #define MTU_ITCR 0xff0 54 #define MTU_ITOP 0xff4 55 56 #define MTU_PERIPH_ID0 0xfe0 57 #define MTU_PERIPH_ID1 0xfe4 58 #define MTU_PERIPH_ID2 0xfe8 59 #define MTU_PERIPH_ID3 0xfeC 60 61 #define MTU_PCELL0 0xff0 62 #define MTU_PCELL1 0xff4 63 #define MTU_PCELL2 0xff8 64 #define MTU_PCELL3 0xffC 65 66 static void __iomem *mtu_base; 67 static bool clkevt_periodic; 68 static u32 clk_prescale; 69 static u32 nmdk_cycle; /* write-once */ 70 static struct delay_timer mtu_delay_timer; 71 72 /* 73 * Override the global weak sched_clock symbol with this 74 * local implementation which uses the clocksource to get some 75 * better resolution when scheduling the kernel. 76 */ 77 static u64 notrace nomadik_read_sched_clock(void) 78 { 79 if (unlikely(!mtu_base)) 80 return 0; 81 82 return -readl(mtu_base + MTU_VAL(0)); 83 } 84 85 static unsigned long nmdk_timer_read_current_timer(void) 86 { 87 return ~readl_relaxed(mtu_base + MTU_VAL(0)); 88 } 89 90 /* Clockevent device: use one-shot mode */ 91 static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev) 92 { 93 writel(1 << 1, mtu_base + MTU_IMSC); 94 writel(evt, mtu_base + MTU_LR(1)); 95 /* Load highest value, enable device, enable interrupts */ 96 writel(MTU_CRn_ONESHOT | clk_prescale | 97 MTU_CRn_32BITS | MTU_CRn_ENA, 98 mtu_base + MTU_CR(1)); 99 100 return 0; 101 } 102 103 static void nmdk_clkevt_reset(void) 104 { 105 if (clkevt_periodic) { 106 /* Timer: configure load and background-load, and fire it up */ 107 writel(nmdk_cycle, mtu_base + MTU_LR(1)); 108 writel(nmdk_cycle, mtu_base + MTU_BGLR(1)); 109 110 writel(MTU_CRn_PERIODIC | clk_prescale | 111 MTU_CRn_32BITS | MTU_CRn_ENA, 112 mtu_base + MTU_CR(1)); 113 writel(1 << 1, mtu_base + MTU_IMSC); 114 } else { 115 /* Generate an interrupt to start the clockevent again */ 116 (void) nmdk_clkevt_next(nmdk_cycle, NULL); 117 } 118 } 119 120 static int nmdk_clkevt_shutdown(struct clock_event_device *evt) 121 { 122 writel(0, mtu_base + MTU_IMSC); 123 /* disable timer */ 124 writel(0, mtu_base + MTU_CR(1)); 125 /* load some high default value */ 126 writel(0xffffffff, mtu_base + MTU_LR(1)); 127 return 0; 128 } 129 130 static int nmdk_clkevt_set_oneshot(struct clock_event_device *evt) 131 { 132 clkevt_periodic = false; 133 return 0; 134 } 135 136 static int nmdk_clkevt_set_periodic(struct clock_event_device *evt) 137 { 138 clkevt_periodic = true; 139 nmdk_clkevt_reset(); 140 return 0; 141 } 142 143 static void nmdk_clksrc_reset(void) 144 { 145 /* Disable */ 146 writel(0, mtu_base + MTU_CR(0)); 147 148 /* ClockSource: configure load and background-load, and fire it up */ 149 writel(nmdk_cycle, mtu_base + MTU_LR(0)); 150 writel(nmdk_cycle, mtu_base + MTU_BGLR(0)); 151 152 writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA, 153 mtu_base + MTU_CR(0)); 154 } 155 156 static void nmdk_clkevt_resume(struct clock_event_device *cedev) 157 { 158 nmdk_clkevt_reset(); 159 nmdk_clksrc_reset(); 160 } 161 162 static struct clock_event_device nmdk_clkevt = { 163 .name = "mtu_1", 164 .features = CLOCK_EVT_FEAT_ONESHOT | 165 CLOCK_EVT_FEAT_PERIODIC | 166 CLOCK_EVT_FEAT_DYNIRQ, 167 .rating = 200, 168 .set_state_shutdown = nmdk_clkevt_shutdown, 169 .set_state_periodic = nmdk_clkevt_set_periodic, 170 .set_state_oneshot = nmdk_clkevt_set_oneshot, 171 .set_next_event = nmdk_clkevt_next, 172 .resume = nmdk_clkevt_resume, 173 }; 174 175 /* 176 * IRQ Handler for timer 1 of the MTU block. 177 */ 178 static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id) 179 { 180 struct clock_event_device *evdev = dev_id; 181 182 writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */ 183 evdev->event_handler(evdev); 184 return IRQ_HANDLED; 185 } 186 187 static struct irqaction nmdk_timer_irq = { 188 .name = "Nomadik Timer Tick", 189 .flags = IRQF_TIMER, 190 .handler = nmdk_timer_interrupt, 191 .dev_id = &nmdk_clkevt, 192 }; 193 194 static int __init nmdk_timer_init(void __iomem *base, int irq, 195 struct clk *pclk, struct clk *clk) 196 { 197 unsigned long rate; 198 int ret; 199 200 mtu_base = base; 201 202 BUG_ON(clk_prepare_enable(pclk)); 203 BUG_ON(clk_prepare_enable(clk)); 204 205 /* 206 * Tick rate is 2.4MHz for Nomadik and 2.4Mhz, 100MHz or 133 MHz 207 * for ux500. 208 * Use a divide-by-16 counter if the tick rate is more than 32MHz. 209 * At 32 MHz, the timer (with 32 bit counter) can be programmed 210 * to wake-up at a max 127s a head in time. Dividing a 2.4 MHz timer 211 * with 16 gives too low timer resolution. 212 */ 213 rate = clk_get_rate(clk); 214 if (rate > 32000000) { 215 rate /= 16; 216 clk_prescale = MTU_CRn_PRESCALE_16; 217 } else { 218 clk_prescale = MTU_CRn_PRESCALE_1; 219 } 220 221 /* Cycles for periodic mode */ 222 nmdk_cycle = DIV_ROUND_CLOSEST(rate, HZ); 223 224 225 /* Timer 0 is the free running clocksource */ 226 nmdk_clksrc_reset(); 227 228 ret = clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0", 229 rate, 200, 32, clocksource_mmio_readl_down); 230 if (ret) { 231 pr_err("timer: failed to initialize clock source %s\n", "mtu_0"); 232 return ret; 233 } 234 235 sched_clock_register(nomadik_read_sched_clock, 32, rate); 236 237 /* Timer 1 is used for events, register irq and clockevents */ 238 setup_irq(irq, &nmdk_timer_irq); 239 nmdk_clkevt.cpumask = cpumask_of(0); 240 nmdk_clkevt.irq = irq; 241 clockevents_config_and_register(&nmdk_clkevt, rate, 2, 0xffffffffU); 242 243 mtu_delay_timer.read_current_timer = &nmdk_timer_read_current_timer; 244 mtu_delay_timer.freq = rate; 245 register_current_timer_delay(&mtu_delay_timer); 246 247 return 0; 248 } 249 250 static int __init nmdk_timer_of_init(struct device_node *node) 251 { 252 struct clk *pclk; 253 struct clk *clk; 254 void __iomem *base; 255 int irq; 256 257 base = of_iomap(node, 0); 258 if (!base) { 259 pr_err("Can't remap registers\n"); 260 return -ENXIO; 261 } 262 263 pclk = of_clk_get_by_name(node, "apb_pclk"); 264 if (IS_ERR(pclk)) { 265 pr_err("could not get apb_pclk\n"); 266 return PTR_ERR(pclk); 267 } 268 269 clk = of_clk_get_by_name(node, "timclk"); 270 if (IS_ERR(clk)) { 271 pr_err("could not get timclk\n"); 272 return PTR_ERR(clk); 273 } 274 275 irq = irq_of_parse_and_map(node, 0); 276 if (irq <= 0) { 277 pr_err("Can't parse IRQ\n"); 278 return -EINVAL; 279 } 280 281 return nmdk_timer_init(base, irq, pclk, clk); 282 } 283 TIMER_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu", 284 nmdk_timer_of_init); 285