1 /* 2 * arch/arm/mach-at91/pm.c 3 * AT91 Power Management 4 * 5 * Copyright (C) 2005 David Brownell 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License as published by 9 * the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 */ 12 13 #include <linux/gpio.h> 14 #include <linux/suspend.h> 15 #include <linux/sched.h> 16 #include <linux/proc_fs.h> 17 #include <linux/interrupt.h> 18 #include <linux/sysfs.h> 19 #include <linux/module.h> 20 #include <linux/platform_device.h> 21 #include <linux/io.h> 22 23 #include <asm/irq.h> 24 #include <linux/atomic.h> 25 #include <asm/mach/time.h> 26 #include <asm/mach/irq.h> 27 28 #include <mach/at91_pmc.h> 29 #include <mach/cpu.h> 30 31 #include "at91_aic.h" 32 #include "generic.h" 33 #include "pm.h" 34 35 /* 36 * Show the reason for the previous system reset. 37 */ 38 39 #include "at91_rstc.h" 40 #include "at91_shdwc.h" 41 42 static void __init show_reset_status(void) 43 { 44 static char reset[] __initdata = "reset"; 45 46 static char general[] __initdata = "general"; 47 static char wakeup[] __initdata = "wakeup"; 48 static char watchdog[] __initdata = "watchdog"; 49 static char software[] __initdata = "software"; 50 static char user[] __initdata = "user"; 51 static char unknown[] __initdata = "unknown"; 52 53 static char signal[] __initdata = "signal"; 54 static char rtc[] __initdata = "rtc"; 55 static char rtt[] __initdata = "rtt"; 56 static char restore[] __initdata = "power-restored"; 57 58 char *reason, *r2 = reset; 59 u32 reset_type, wake_type; 60 61 if (!at91_shdwc_base || !at91_rstc_base) 62 return; 63 64 reset_type = at91_rstc_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP; 65 wake_type = at91_shdwc_read(AT91_SHDW_SR); 66 67 switch (reset_type) { 68 case AT91_RSTC_RSTTYP_GENERAL: 69 reason = general; 70 break; 71 case AT91_RSTC_RSTTYP_WAKEUP: 72 /* board-specific code enabled the wakeup sources */ 73 reason = wakeup; 74 75 /* "wakeup signal" */ 76 if (wake_type & AT91_SHDW_WAKEUP0) 77 r2 = signal; 78 else { 79 r2 = reason; 80 if (wake_type & AT91_SHDW_RTTWK) /* rtt wakeup */ 81 reason = rtt; 82 else if (wake_type & AT91_SHDW_RTCWK) /* rtc wakeup */ 83 reason = rtc; 84 else if (wake_type == 0) /* power-restored wakeup */ 85 reason = restore; 86 else /* unknown wakeup */ 87 reason = unknown; 88 } 89 break; 90 case AT91_RSTC_RSTTYP_WATCHDOG: 91 reason = watchdog; 92 break; 93 case AT91_RSTC_RSTTYP_SOFTWARE: 94 reason = software; 95 break; 96 case AT91_RSTC_RSTTYP_USER: 97 reason = user; 98 break; 99 default: 100 reason = unknown; 101 break; 102 } 103 pr_info("AT91: Starting after %s %s\n", reason, r2); 104 } 105 106 static int at91_pm_valid_state(suspend_state_t state) 107 { 108 switch (state) { 109 case PM_SUSPEND_ON: 110 case PM_SUSPEND_STANDBY: 111 case PM_SUSPEND_MEM: 112 return 1; 113 114 default: 115 return 0; 116 } 117 } 118 119 120 static suspend_state_t target_state; 121 122 /* 123 * Called after processes are frozen, but before we shutdown devices. 124 */ 125 static int at91_pm_begin(suspend_state_t state) 126 { 127 target_state = state; 128 return 0; 129 } 130 131 /* 132 * Verify that all the clocks are correct before entering 133 * slow-clock mode. 134 */ 135 static int at91_pm_verify_clocks(void) 136 { 137 unsigned long scsr; 138 int i; 139 140 scsr = at91_pmc_read(AT91_PMC_SCSR); 141 142 /* USB must not be using PLLB */ 143 if (cpu_is_at91rm9200()) { 144 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) { 145 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n"); 146 return 0; 147 } 148 } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263() 149 || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) { 150 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) { 151 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n"); 152 return 0; 153 } 154 } 155 156 if (!IS_ENABLED(CONFIG_AT91_PROGRAMMABLE_CLOCKS)) 157 return 1; 158 159 /* PCK0..PCK3 must be disabled, or configured to use clk32k */ 160 for (i = 0; i < 4; i++) { 161 u32 css; 162 163 if ((scsr & (AT91_PMC_PCK0 << i)) == 0) 164 continue; 165 166 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS; 167 if (css != AT91_PMC_CSS_SLOW) { 168 pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css); 169 return 0; 170 } 171 } 172 173 return 1; 174 } 175 176 /* 177 * Call this from platform driver suspend() to see how deeply to suspend. 178 * For example, some controllers (like OHCI) need one of the PLL clocks 179 * in order to act as a wakeup source, and those are not available when 180 * going into slow clock mode. 181 * 182 * REVISIT: generalize as clk_will_be_available(clk)? Other platforms have 183 * the very same problem (but not using at91 main_clk), and it'd be better 184 * to add one generic API rather than lots of platform-specific ones. 185 */ 186 int at91_suspend_entering_slow_clock(void) 187 { 188 return (target_state == PM_SUSPEND_MEM); 189 } 190 EXPORT_SYMBOL(at91_suspend_entering_slow_clock); 191 192 193 static void (*slow_clock)(void __iomem *pmc, void __iomem *ramc0, 194 void __iomem *ramc1, int memctrl); 195 196 #ifdef CONFIG_AT91_SLOW_CLOCK 197 extern void at91_slow_clock(void __iomem *pmc, void __iomem *ramc0, 198 void __iomem *ramc1, int memctrl); 199 extern u32 at91_slow_clock_sz; 200 #endif 201 202 static int at91_pm_enter(suspend_state_t state) 203 { 204 if (of_have_populated_dt()) 205 at91_pinctrl_gpio_suspend(); 206 else 207 at91_gpio_suspend(); 208 at91_irq_suspend(); 209 210 pr_debug("AT91: PM - wake mask %08x, pm state %d\n", 211 /* remember all the always-wake irqs */ 212 (at91_pmc_read(AT91_PMC_PCSR) 213 | (1 << AT91_ID_FIQ) 214 | (1 << AT91_ID_SYS) 215 | (at91_extern_irq)) 216 & at91_aic_read(AT91_AIC_IMR), 217 state); 218 219 switch (state) { 220 /* 221 * Suspend-to-RAM is like STANDBY plus slow clock mode, so 222 * drivers must suspend more deeply: only the master clock 223 * controller may be using the main oscillator. 224 */ 225 case PM_SUSPEND_MEM: 226 /* 227 * Ensure that clocks are in a valid state. 228 */ 229 if (!at91_pm_verify_clocks()) 230 goto error; 231 232 /* 233 * Enter slow clock mode by switching over to clk32k and 234 * turning off the main oscillator; reverse on wakeup. 235 */ 236 if (slow_clock) { 237 int memctrl = AT91_MEMCTRL_SDRAMC; 238 239 if (cpu_is_at91rm9200()) 240 memctrl = AT91_MEMCTRL_MC; 241 else if (cpu_is_at91sam9g45()) 242 memctrl = AT91_MEMCTRL_DDRSDR; 243 #ifdef CONFIG_AT91_SLOW_CLOCK 244 /* copy slow_clock handler to SRAM, and call it */ 245 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz); 246 #endif 247 slow_clock(at91_pmc_base, at91_ramc_base[0], 248 at91_ramc_base[1], memctrl); 249 break; 250 } else { 251 pr_info("AT91: PM - no slow clock mode enabled ...\n"); 252 /* FALLTHROUGH leaving master clock alone */ 253 } 254 255 /* 256 * STANDBY mode has *all* drivers suspended; ignores irqs not 257 * marked as 'wakeup' event sources; and reduces DRAM power. 258 * But otherwise it's identical to PM_SUSPEND_ON: cpu idle, and 259 * nothing fancy done with main or cpu clocks. 260 */ 261 case PM_SUSPEND_STANDBY: 262 /* 263 * NOTE: the Wait-for-Interrupt instruction needs to be 264 * in icache so no SDRAM accesses are needed until the 265 * wakeup IRQ occurs and self-refresh is terminated. 266 * For ARM 926 based chips, this requirement is weaker 267 * as at91sam9 can access a RAM in self-refresh mode. 268 */ 269 if (cpu_is_at91rm9200()) 270 at91rm9200_standby(); 271 else if (cpu_is_at91sam9g45()) 272 at91sam9g45_standby(); 273 else if (cpu_is_at91sam9263()) 274 at91sam9263_standby(); 275 else 276 at91sam9_standby(); 277 break; 278 279 case PM_SUSPEND_ON: 280 cpu_do_idle(); 281 break; 282 283 default: 284 pr_debug("AT91: PM - bogus suspend state %d\n", state); 285 goto error; 286 } 287 288 pr_debug("AT91: PM - wakeup %08x\n", 289 at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR)); 290 291 error: 292 target_state = PM_SUSPEND_ON; 293 at91_irq_resume(); 294 if (of_have_populated_dt()) 295 at91_pinctrl_gpio_resume(); 296 else 297 at91_gpio_resume(); 298 return 0; 299 } 300 301 /* 302 * Called right prior to thawing processes. 303 */ 304 static void at91_pm_end(void) 305 { 306 target_state = PM_SUSPEND_ON; 307 } 308 309 310 static const struct platform_suspend_ops at91_pm_ops = { 311 .valid = at91_pm_valid_state, 312 .begin = at91_pm_begin, 313 .enter = at91_pm_enter, 314 .end = at91_pm_end, 315 }; 316 317 static int __init at91_pm_init(void) 318 { 319 #ifdef CONFIG_AT91_SLOW_CLOCK 320 slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz); 321 #endif 322 323 pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : "")); 324 325 /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */ 326 if (cpu_is_at91rm9200()) 327 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0); 328 329 suspend_set_ops(&at91_pm_ops); 330 331 show_reset_status(); 332 return 0; 333 } 334 arch_initcall(at91_pm_init); 335