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 <linux/mc146818rtc.h> 18 19 #include "internal.h" 20 21 ACPI_MODULE_NAME("cmos rtc"); 22 23 static const struct acpi_device_id acpi_cmos_rtc_ids[] = { 24 { "PNP0B00" }, 25 { "PNP0B01" }, 26 { "PNP0B02" }, 27 {} 28 }; 29 30 static acpi_status 31 acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address, 32 u32 bits, u64 *value64, 33 void *handler_context, void *region_context) 34 { 35 int i; 36 u8 *value = (u8 *)value64; 37 38 if (address > 0xff || !value64) 39 return AE_BAD_PARAMETER; 40 41 if (function != ACPI_WRITE && function != ACPI_READ) 42 return AE_BAD_PARAMETER; 43 44 spin_lock_irq(&rtc_lock); 45 46 for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value) 47 if (function == ACPI_READ) 48 *value = CMOS_READ(address); 49 else 50 CMOS_WRITE(*value, address); 51 52 spin_unlock_irq(&rtc_lock); 53 54 return AE_OK; 55 } 56 57 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev, 58 const struct acpi_device_id *id) 59 { 60 acpi_status status; 61 62 status = acpi_install_address_space_handler(adev->handle, 63 ACPI_ADR_SPACE_CMOS, 64 &acpi_cmos_rtc_space_handler, 65 NULL, NULL); 66 if (ACPI_FAILURE(status)) { 67 pr_err(PREFIX "Error installing CMOS-RTC region handler\n"); 68 return -ENODEV; 69 } 70 71 return 1; 72 } 73 74 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev) 75 { 76 if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle, 77 ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler))) 78 pr_err(PREFIX "Error removing CMOS-RTC region handler\n"); 79 } 80 81 static struct acpi_scan_handler cmos_rtc_handler = { 82 .ids = acpi_cmos_rtc_ids, 83 .attach = acpi_install_cmos_rtc_space_handler, 84 .detach = acpi_remove_cmos_rtc_space_handler, 85 }; 86 87 void __init acpi_cmos_rtc_init(void) 88 { 89 acpi_scan_add_handler(&cmos_rtc_handler); 90 } 91