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