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/platform_data/clocksource-nomadik-mtu.h> 24 #include <linux/sched_clock.h> 25 #include <asm/mach/time.h> 26 27 /* 28 * The MTU device hosts four different counters, with 4 set of 29 * registers. These are register names. 30 */ 31 32 #define MTU_IMSC 0x00 /* Interrupt mask set/clear */ 33 #define MTU_RIS 0x04 /* Raw interrupt status */ 34 #define MTU_MIS 0x08 /* Masked interrupt status */ 35 #define MTU_ICR 0x0C /* Interrupt clear register */ 36 37 /* per-timer registers take 0..3 as argument */ 38 #define MTU_LR(x) (0x10 + 0x10 * (x) + 0x00) /* Load value */ 39 #define MTU_VAL(x) (0x10 + 0x10 * (x) + 0x04) /* Current value */ 40 #define MTU_CR(x) (0x10 + 0x10 * (x) + 0x08) /* Control reg */ 41 #define MTU_BGLR(x) (0x10 + 0x10 * (x) + 0x0c) /* At next overflow */ 42 43 /* bits for the control register */ 44 #define MTU_CRn_ENA 0x80 45 #define MTU_CRn_PERIODIC 0x40 /* if 0 = free-running */ 46 #define MTU_CRn_PRESCALE_MASK 0x0c 47 #define MTU_CRn_PRESCALE_1 0x00 48 #define MTU_CRn_PRESCALE_16 0x04 49 #define MTU_CRn_PRESCALE_256 0x08 50 #define MTU_CRn_32BITS 0x02 51 #define MTU_CRn_ONESHOT 0x01 /* if 0 = wraps reloading from BGLR*/ 52 53 /* Other registers are usual amba/primecell registers, currently not used */ 54 #define MTU_ITCR 0xff0 55 #define MTU_ITOP 0xff4 56 57 #define MTU_PERIPH_ID0 0xfe0 58 #define MTU_PERIPH_ID1 0xfe4 59 #define MTU_PERIPH_ID2 0xfe8 60 #define MTU_PERIPH_ID3 0xfeC 61 62 #define MTU_PCELL0 0xff0 63 #define MTU_PCELL1 0xff4 64 #define MTU_PCELL2 0xff8 65 #define MTU_PCELL3 0xffC 66 67 static void __iomem *mtu_base; 68 static bool clkevt_periodic; 69 static u32 clk_prescale; 70 static u32 nmdk_cycle; /* write-once */ 71 static struct delay_timer mtu_delay_timer; 72 73 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK 74 /* 75 * Override the global weak sched_clock symbol with this 76 * local implementation which uses the clocksource to get some 77 * better resolution when scheduling the kernel. 78 */ 79 static u64 notrace nomadik_read_sched_clock(void) 80 { 81 if (unlikely(!mtu_base)) 82 return 0; 83 84 return -readl(mtu_base + MTU_VAL(0)); 85 } 86 #endif 87 88 static unsigned long nmdk_timer_read_current_timer(void) 89 { 90 return ~readl_relaxed(mtu_base + MTU_VAL(0)); 91 } 92 93 /* Clockevent device: use one-shot mode */ 94 static int nmdk_clkevt_next(unsigned long evt, struct clock_event_device *ev) 95 { 96 writel(1 << 1, mtu_base + MTU_IMSC); 97 writel(evt, mtu_base + MTU_LR(1)); 98 /* Load highest value, enable device, enable interrupts */ 99 writel(MTU_CRn_ONESHOT | clk_prescale | 100 MTU_CRn_32BITS | MTU_CRn_ENA, 101 mtu_base + MTU_CR(1)); 102 103 return 0; 104 } 105 106 void nmdk_clkevt_reset(void) 107 { 108 if (clkevt_periodic) { 109 /* Timer: configure load and background-load, and fire it up */ 110 writel(nmdk_cycle, mtu_base + MTU_LR(1)); 111 writel(nmdk_cycle, mtu_base + MTU_BGLR(1)); 112 113 writel(MTU_CRn_PERIODIC | clk_prescale | 114 MTU_CRn_32BITS | MTU_CRn_ENA, 115 mtu_base + MTU_CR(1)); 116 writel(1 << 1, mtu_base + MTU_IMSC); 117 } else { 118 /* Generate an interrupt to start the clockevent again */ 119 (void) nmdk_clkevt_next(nmdk_cycle, NULL); 120 } 121 } 122 123 static void nmdk_clkevt_mode(enum clock_event_mode mode, 124 struct clock_event_device *dev) 125 { 126 switch (mode) { 127 case CLOCK_EVT_MODE_PERIODIC: 128 clkevt_periodic = true; 129 nmdk_clkevt_reset(); 130 break; 131 case CLOCK_EVT_MODE_ONESHOT: 132 clkevt_periodic = false; 133 break; 134 case CLOCK_EVT_MODE_SHUTDOWN: 135 case CLOCK_EVT_MODE_UNUSED: 136 writel(0, mtu_base + MTU_IMSC); 137 /* disable timer */ 138 writel(0, mtu_base + MTU_CR(1)); 139 /* load some high default value */ 140 writel(0xffffffff, mtu_base + MTU_LR(1)); 141 break; 142 case CLOCK_EVT_MODE_RESUME: 143 break; 144 } 145 } 146 147 void nmdk_clksrc_reset(void) 148 { 149 /* Disable */ 150 writel(0, mtu_base + MTU_CR(0)); 151 152 /* ClockSource: configure load and background-load, and fire it up */ 153 writel(nmdk_cycle, mtu_base + MTU_LR(0)); 154 writel(nmdk_cycle, mtu_base + MTU_BGLR(0)); 155 156 writel(clk_prescale | MTU_CRn_32BITS | MTU_CRn_ENA, 157 mtu_base + MTU_CR(0)); 158 } 159 160 static void nmdk_clkevt_resume(struct clock_event_device *cedev) 161 { 162 nmdk_clkevt_reset(); 163 nmdk_clksrc_reset(); 164 } 165 166 static struct clock_event_device nmdk_clkevt = { 167 .name = "mtu_1", 168 .features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_PERIODIC | 169 CLOCK_EVT_FEAT_DYNIRQ, 170 .rating = 200, 171 .set_mode = nmdk_clkevt_mode, 172 .set_next_event = nmdk_clkevt_next, 173 .resume = nmdk_clkevt_resume, 174 }; 175 176 /* 177 * IRQ Handler for timer 1 of the MTU block. 178 */ 179 static irqreturn_t nmdk_timer_interrupt(int irq, void *dev_id) 180 { 181 struct clock_event_device *evdev = dev_id; 182 183 writel(1 << 1, mtu_base + MTU_ICR); /* Interrupt clear reg */ 184 evdev->event_handler(evdev); 185 return IRQ_HANDLED; 186 } 187 188 static struct irqaction nmdk_timer_irq = { 189 .name = "Nomadik Timer Tick", 190 .flags = IRQF_DISABLED | IRQF_TIMER, 191 .handler = nmdk_timer_interrupt, 192 .dev_id = &nmdk_clkevt, 193 }; 194 195 static void __init __nmdk_timer_init(void __iomem *base, int irq, 196 struct clk *pclk, struct clk *clk) 197 { 198 unsigned long rate; 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 if (clocksource_mmio_init(mtu_base + MTU_VAL(0), "mtu_0", 229 rate, 200, 32, clocksource_mmio_readl_down)) 230 pr_err("timer: failed to initialize clock source %s\n", 231 "mtu_0"); 232 233 #ifdef CONFIG_CLKSRC_NOMADIK_MTU_SCHED_CLOCK 234 sched_clock_register(nomadik_read_sched_clock, 32, rate); 235 #endif 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 } 247 248 void __init nmdk_timer_init(void __iomem *base, int irq) 249 { 250 struct clk *clk0, *pclk0; 251 252 pclk0 = clk_get_sys("mtu0", "apb_pclk"); 253 BUG_ON(IS_ERR(pclk0)); 254 clk0 = clk_get_sys("mtu0", NULL); 255 BUG_ON(IS_ERR(clk0)); 256 257 __nmdk_timer_init(base, irq, pclk0, clk0); 258 } 259 260 static void __init nmdk_timer_of_init(struct device_node *node) 261 { 262 struct clk *pclk; 263 struct clk *clk; 264 void __iomem *base; 265 int irq; 266 267 base = of_iomap(node, 0); 268 if (!base) 269 panic("Can't remap registers"); 270 271 pclk = of_clk_get_by_name(node, "apb_pclk"); 272 if (IS_ERR(pclk)) 273 panic("could not get apb_pclk"); 274 275 clk = of_clk_get_by_name(node, "timclk"); 276 if (IS_ERR(clk)) 277 panic("could not get timclk"); 278 279 irq = irq_of_parse_and_map(node, 0); 280 if (irq <= 0) 281 panic("Can't parse IRQ"); 282 283 __nmdk_timer_init(base, irq, pclk, clk); 284 } 285 CLOCKSOURCE_OF_DECLARE(nomadik_mtu, "st,nomadik-mtu", 286 nmdk_timer_of_init); 287