1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ACPI support for CMOS RTC Address Space access 4 * 5 * Copyright (C) 2013, Intel Corporation 6 * Authors: Lan Tianyu <tianyu.lan@intel.com> 7 */ 8 9 #include <linux/acpi.h> 10 #include <linux/device.h> 11 #include <linux/err.h> 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/mc146818rtc.h> 15 16 #include "internal.h" 17 18 ACPI_MODULE_NAME("cmos rtc"); 19 20 static const struct acpi_device_id acpi_cmos_rtc_ids[] = { 21 { "PNP0B00" }, 22 { "PNP0B01" }, 23 { "PNP0B02" }, 24 {} 25 }; 26 27 static acpi_status 28 acpi_cmos_rtc_space_handler(u32 function, acpi_physical_address address, 29 u32 bits, u64 *value64, 30 void *handler_context, void *region_context) 31 { 32 int i; 33 u8 *value = (u8 *)value64; 34 35 if (address > 0xff || !value64) 36 return AE_BAD_PARAMETER; 37 38 if (function != ACPI_WRITE && function != ACPI_READ) 39 return AE_BAD_PARAMETER; 40 41 spin_lock_irq(&rtc_lock); 42 43 for (i = 0; i < DIV_ROUND_UP(bits, 8); ++i, ++address, ++value) 44 if (function == ACPI_READ) 45 *value = CMOS_READ(address); 46 else 47 CMOS_WRITE(*value, address); 48 49 spin_unlock_irq(&rtc_lock); 50 51 return AE_OK; 52 } 53 54 static int acpi_install_cmos_rtc_space_handler(struct acpi_device *adev, 55 const struct acpi_device_id *id) 56 { 57 acpi_status status; 58 59 status = acpi_install_address_space_handler(adev->handle, 60 ACPI_ADR_SPACE_CMOS, 61 &acpi_cmos_rtc_space_handler, 62 NULL, NULL); 63 if (ACPI_FAILURE(status)) { 64 pr_err(PREFIX "Error installing CMOS-RTC region handler\n"); 65 return -ENODEV; 66 } 67 68 return 1; 69 } 70 71 static void acpi_remove_cmos_rtc_space_handler(struct acpi_device *adev) 72 { 73 if (ACPI_FAILURE(acpi_remove_address_space_handler(adev->handle, 74 ACPI_ADR_SPACE_CMOS, &acpi_cmos_rtc_space_handler))) 75 pr_err(PREFIX "Error removing CMOS-RTC region handler\n"); 76 } 77 78 static struct acpi_scan_handler cmos_rtc_handler = { 79 .ids = acpi_cmos_rtc_ids, 80 .attach = acpi_install_cmos_rtc_space_handler, 81 .detach = acpi_remove_cmos_rtc_space_handler, 82 }; 83 84 void __init acpi_cmos_rtc_init(void) 85 { 86 acpi_scan_add_handler(&cmos_rtc_handler); 87 } 88