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/module.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/pm.h>
  12 #include <linux/regmap.h>
  13 #include <linux/syscore_ops.h>
  14
  15 #define SC27XX_PWR_PD_HW        0xc2c
  16 #define SC27XX_PWR_OFF_EN       BIT(0)
  17 #define SC27XX_SLP_CTRL         0xdf0
  18 #define SC27XX_LDO_XTL_EN       BIT(3)
  19
  20 static struct regmap *regmap;
  21
  22 /*
  23  * On Spreadtrum platform, we need power off system through external SC27xx
  24  * series PMICs, and it is one similar SPI bus mapped by regmap to access PMIC,
  25  * which is not fast io access.
  26  *
  27  * So before stopping other cores, we need release other cores' resource by
  28  * taking cpus down to avoid racing regmap or spi mutex lock when poweroff
  29  * system through PMIC.
  30  */
  31 static void sc27xx_poweroff_shutdown(void)
  32 {
  33 #ifdef CONFIG_HOTPLUG_CPU
  34         int cpu;
  35
  36         for_each_online_cpu(cpu) {
  37                 if (cpu != smp_processor_id())
  38                         remove_cpu(cpu);
  39         }
  40 #endif
  41 }
  42
  43 static struct syscore_ops poweroff_syscore_ops = {
  44         .shutdown = sc27xx_poweroff_shutdown,
  45 };
  46
  47 static void sc27xx_poweroff_do_poweroff(void)
  48 {
  49         /* Disable the external subsys connection's power firstly */
  50         regmap_write(regmap, SC27XX_SLP_CTRL, SC27XX_LDO_XTL_EN);
  51
  52         regmap_write(regmap, SC27XX_PWR_PD_HW, SC27XX_PWR_OFF_EN);
  53 }
  54
  55 static int sc27xx_poweroff_probe(struct platform_device *pdev)
  56 {
  57         if (regmap)
  58                 return -EINVAL;
  59
  60         regmap = dev_get_regmap(pdev->dev.parent, NULL);
  61         if (!regmap)
  62                 return -ENODEV;
  63
  64         pm_power_off = sc27xx_poweroff_do_poweroff;
  65         register_syscore_ops(&poweroff_syscore_ops);
  66         return 0;
  67 }
  68
  69 static struct platform_driver sc27xx_poweroff_driver = {
  70         .probe = sc27xx_poweroff_probe,
  71         .driver = {
  72                 .name = "sc27xx-poweroff",
  73         },
  74 };
  75 module_platform_driver(sc27xx_poweroff_driver);
  76
  77 MODULE_DESCRIPTION("Power off driver for SC27XX PMIC Device");
  78 MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
  79 MODULE_LICENSE("GPL v2");