1 // SPDX-License-Identifier: GPL-2.0 2 // LPC variant I/O for Microchip EC 3 // 4 // Copyright (C) 2016 Google, Inc 5 6 #include <linux/delay.h> 7 #include <linux/io.h> 8 #include <linux/mutex.h> 9 #include <linux/types.h> 10 11 #include "cros_ec_lpc_mec.h" 12 13 /* 14 * This mutex must be held while accessing the EMI unit. We can't rely on the 15 * EC mutex because memmap data may be accessed without it being held. 16 */ 17 static struct mutex io_mutex; 18 static u16 mec_emi_base, mec_emi_end; 19 20 /** 21 * cros_ec_lpc_mec_emi_write_address() - Initialize EMI at a given address. 22 * 23 * @addr: Starting read / write address 24 * @access_type: Type of access, typically 32-bit auto-increment 25 */ 26 static void cros_ec_lpc_mec_emi_write_address(u16 addr, 27 enum cros_ec_lpc_mec_emi_access_mode access_type) 28 { 29 outb((addr & 0xfc) | access_type, MEC_EMI_EC_ADDRESS_B0(mec_emi_base)); 30 outb((addr >> 8) & 0x7f, MEC_EMI_EC_ADDRESS_B1(mec_emi_base)); 31 } 32 33 /** 34 * cros_ec_lpc_mec_in_range() - Determine if addresses are in MEC EMI range. 35 * 36 * @offset: Address offset 37 * @length: Number of bytes to check 38 * 39 * Return: 1 if in range, 0 if not, and -EINVAL on failure 40 * such as the mec range not being initialized 41 */ 42 int cros_ec_lpc_mec_in_range(unsigned int offset, unsigned int length) 43 { 44 if (length == 0) 45 return -EINVAL; 46 47 if (WARN_ON(mec_emi_base == 0 || mec_emi_end == 0)) 48 return -EINVAL; 49 50 if (offset >= mec_emi_base && offset < mec_emi_end) { 51 if (WARN_ON(offset + length - 1 >= mec_emi_end)) 52 return -EINVAL; 53 return 1; 54 } 55 56 if (WARN_ON(offset + length > mec_emi_base && offset < mec_emi_end)) 57 return -EINVAL; 58 59 return 0; 60 } 61 62 /** 63 * cros_ec_lpc_io_bytes_mec() - Read / write bytes to MEC EMI port. 64 * 65 * @io_type: MEC_IO_READ or MEC_IO_WRITE, depending on request 66 * @offset: Base read / write address 67 * @length: Number of bytes to read / write 68 * @buf: Destination / source buffer 69 * 70 * Return: 8-bit checksum of all bytes read / written 71 */ 72 u8 cros_ec_lpc_io_bytes_mec(enum cros_ec_lpc_mec_io_type io_type, 73 unsigned int offset, unsigned int length, 74 u8 *buf) 75 { 76 int i = 0; 77 int io_addr; 78 u8 sum = 0; 79 enum cros_ec_lpc_mec_emi_access_mode access, new_access; 80 81 /* Return checksum of 0 if window is not initialized */ 82 WARN_ON(mec_emi_base == 0 || mec_emi_end == 0); 83 if (mec_emi_base == 0 || mec_emi_end == 0) 84 return 0; 85 86 /* 87 * Long access cannot be used on misaligned data since reading B0 loads 88 * the data register and writing B3 flushes. 89 */ 90 if (offset & 0x3 || length < 4) 91 access = ACCESS_TYPE_BYTE; 92 else 93 access = ACCESS_TYPE_LONG_AUTO_INCREMENT; 94 95 mutex_lock(&io_mutex); 96 97 /* Initialize I/O at desired address */ 98 cros_ec_lpc_mec_emi_write_address(offset, access); 99 100 /* Skip bytes in case of misaligned offset */ 101 io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base) + (offset & 0x3); 102 while (i < length) { 103 while (io_addr <= MEC_EMI_EC_DATA_B3(mec_emi_base)) { 104 if (io_type == MEC_IO_READ) 105 buf[i] = inb(io_addr++); 106 else 107 outb(buf[i], io_addr++); 108 109 sum += buf[i++]; 110 offset++; 111 112 /* Extra bounds check in case of misaligned length */ 113 if (i == length) 114 goto done; 115 } 116 117 /* 118 * Use long auto-increment access except for misaligned write, 119 * since writing B3 triggers the flush. 120 */ 121 if (length - i < 4 && io_type == MEC_IO_WRITE) 122 new_access = ACCESS_TYPE_BYTE; 123 else 124 new_access = ACCESS_TYPE_LONG_AUTO_INCREMENT; 125 126 if (new_access != access || 127 access != ACCESS_TYPE_LONG_AUTO_INCREMENT) { 128 access = new_access; 129 cros_ec_lpc_mec_emi_write_address(offset, access); 130 } 131 132 /* Access [B0, B3] on each loop pass */ 133 io_addr = MEC_EMI_EC_DATA_B0(mec_emi_base); 134 } 135 136 done: 137 mutex_unlock(&io_mutex); 138 139 return sum; 140 } 141 EXPORT_SYMBOL(cros_ec_lpc_io_bytes_mec); 142 143 void cros_ec_lpc_mec_init(unsigned int base, unsigned int end) 144 { 145 mutex_init(&io_mutex); 146 mec_emi_base = base; 147 mec_emi_end = end; 148 } 149 EXPORT_SYMBOL(cros_ec_lpc_mec_init); 150 151 void cros_ec_lpc_mec_destroy(void) 152 { 153 mutex_destroy(&io_mutex); 154 } 155 EXPORT_SYMBOL(cros_ec_lpc_mec_destroy); 156