drivers/power/reset/sc27xx-poweroff.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2018 Spreadtrum Communications Inc.
   4  * Copyright (C) 2018 Linaro Ltd.
   5  */
   6
   7 #include <linux/cpu.h>
   8 #include <linux/kernel.h>
   9 #include <linux/platform_device.h>
  10 #include <linux/pm.h>
  11 #include <linux/regmap.h>
  12 #include <linux/syscore_ops.h>
  13
  14 #define SC27XX_PWR_PD_HW        0xc2c
  15 #define SC27XX_PWR_OFF_EN       BIT(0)
  16
  17 static struct regmap *regmap;
  18
  19 /*
  20  * On Spreadtrum platform, we need power off system through external SC27xx
  21  * series PMICs, and it is one similar SPI bus mapped by regmap to access PMIC,
  22  * which is not fast io access.
  23  *
  24  * So before stopping other cores, we need release other cores' resource by
  25  * taking cpus down to avoid racing regmap or spi mutex lock when poweroff
  26  * system through PMIC.
  27  */
  28 static void sc27xx_poweroff_shutdown(void)
  29 {
  30 #ifdef CONFIG_PM_SLEEP_SMP
  31         int cpu = smp_processor_id();
  32
  33         freeze_secondary_cpus(cpu);
  34 #endif
  35 }
  36
  37 static struct syscore_ops poweroff_syscore_ops = {
  38         .shutdown = sc27xx_poweroff_shutdown,
  39 };
  40
  41 static void sc27xx_poweroff_do_poweroff(void)
  42 {
  43         regmap_write(regmap, SC27XX_PWR_PD_HW, SC27XX_PWR_OFF_EN);
  44 }
  45
  46 static int sc27xx_poweroff_probe(struct platform_device *pdev)
  47 {
  48         if (regmap)
  49                 return -EINVAL;
  50
  51         regmap = dev_get_regmap(pdev->dev.parent, NULL);
  52         if (!regmap)
  53                 return -ENODEV;
  54
  55         pm_power_off = sc27xx_poweroff_do_poweroff;
  56         register_syscore_ops(&poweroff_syscore_ops);
  57         return 0;
  58 }
  59
  60 static struct platform_driver sc27xx_poweroff_driver = {
  61         .probe = sc27xx_poweroff_probe,
  62         .driver = {
  63                 .name = "sc27xx-poweroff",
  64         },
  65 };
  66 builtin_platform_driver(sc27xx_poweroff_driver);