1 /* 2 * ACPI support for CMOS RTC Address Space access 3 * 4 * Copyright (C) 2013, Intel Corporation 5 * Authors: Lan Tianyu <tianyu.lan@intel.com> 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 version 2 as 9 * published by the Free Software Foundation. 10 */ 11 12 #include <linux/acpi.h> 13 #include <linux/device.h> 14 #include <linux/err.h> 15 #include <linux/kernel.h> 16 #include <linux/module.h> 17 #include <asm-generic/rtc.h> 18 19 #include "internal.h" 20 21 #define PREFIX "ACPI: " 22 23 ACPI_MODULE_NAME("cmos rtc"); 24 25 static const struct acpi_device_id acpi_cmos_rtc_ids[] = { 26 { "PNP0B00" }, 27 { "PNP0B01" }, 28 { "PNP0B02" }, 29 {} 30 }; 31 32 static acpi_status 33 acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address, 34 u32 bits, u64 *value64, 35 void *handler_context, void *region_context) 36 { 37 int i; 38 u8 *value = (u8 *)&value64; 39 40 if (address > 0xff || !value64) 41 return AE_BAD_PARAMETER; 42 43 if (function != ACPI_WRITE && function != ACPI_READ) 44 return AE_BAD_PARAMETER; 45 46 spin_lock_irq(&rtc_lock); 47 48 for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value) 49 if (function == ACPI_READ) 50 *value = CMOS_READ(address); 51 else 52 CMOS_WRITE(*value, address); 53 54 spin_unlock_irq(&rtc_lock); 55 56 return AE_OK; 57 } 58 59 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev, 60 const struct acpi_device_id *id) 61 { 62 acpi_status status; 63 64 status = acpi_install_address_space_handler(adev->handle, 65 ACPI_ADR_SPACE_CMOS, 66 &acpi_cmos_rtc_space_handler, 67 NULL, NULL); 68 if (ACPI_FAILURE(status)) { 69 pr_err(PREFIX "Error installing CMOS-RTC region handler\n"); 70 return -ENODEV; 71 } 72 73 return 0; 74 } 75 76 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev) 77 { 78 if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle, 79 ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler))) 80 pr_err(PREFIX "Error removing CMOS-RTC region handler\n"); 81 } 82 83 static struct acpi_scan_handler cmos_rtc_handler = { 84 .ids = acpi_cmos_rtc_ids, 85 .attach = acpi_install_cmos_rtc_space_handler, 86 .detach = acpi_remove_cmos_rtc_space_handler, 87 }; 88 89 void __init acpi_cmos_rtc_init(void) 90 { 91 acpi_scan_add_handler(&cmos_rtc_handler); 92 } 93