arch/arm/mach-alpine/alpine_cpu_pm.c

   1 /*
   2  * Low-level power-management support for Alpine platform.
   3  *
   4  * Copyright (C) 2015 Annapurna Labs Ltd.
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/io.h>
  18 #include <linux/of.h>
  19 #include <linux/of_address.h>
  20 #include <linux/regmap.h>
  21 #include <linux/mfd/syscon.h>
  22
  23 #include "alpine_cpu_pm.h"
  24 #include "alpine_cpu_resume.h"
  25
  26 /* NB registers */
  27 #define AL_SYSFAB_POWER_CONTROL(cpu)    (0x2000 + (cpu)*0x100 + 0x20)
  28
  29 static struct regmap *al_sysfabric;
  30 static struct al_cpu_resume_regs __iomem *al_cpu_resume_regs;
  31 static int wakeup_supported;
  32
  33 int alpine_cpu_wakeup(unsigned int phys_cpu, uint32_t phys_resume_addr)
  34 {
  35         if (!wakeup_supported)
  36                 return -ENOSYS;
  37
  38         /*
  39          * Set CPU resume address -
  40          * secure firmware running on boot will jump to this address
  41          * after setting proper CPU mode, and initialiing e.g. secure
  42          * regs (the same mode all CPUs are booted to - usually HYP)
  43          */
  44         writel(phys_resume_addr,
  45                &al_cpu_resume_regs->per_cpu[phys_cpu].resume_addr);
  46
  47         /* Power-up the CPU */
  48         regmap_write(al_sysfabric, AL_SYSFAB_POWER_CONTROL(phys_cpu), 0);
  49
  50         return 0;
  51 }
  52
  53 void __init alpine_cpu_pm_init(void)
  54 {
  55         struct device_node *np;
  56         uint32_t watermark;
  57
  58         al_sysfabric = syscon_regmap_lookup_by_compatible("al,alpine-sysfabric-service");
  59
  60         np = of_find_compatible_node(NULL, NULL, "al,alpine-cpu-resume");
  61         al_cpu_resume_regs = of_iomap(np, 0);
  62
  63         wakeup_supported = !IS_ERR(al_sysfabric) && al_cpu_resume_regs;
  64
  65         if (wakeup_supported) {
  66                 watermark = readl(&al_cpu_resume_regs->watermark);
  67                 wakeup_supported = (watermark & AL_CPU_RESUME_MAGIC_NUM_MASK)
  68                                     == AL_CPU_RESUME_MAGIC_NUM;
  69         }
  70 }