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 DEFINE_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(value: (addr & 0xfc) | access_type, MEC_EMI_EC_ADDRESS_B0(mec_emi_base)); |
30 | outb(value: (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(addr: offset, access_type: 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(port: io_addr++); |
106 | else |
107 | outb(value: buf[i], port: 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(addr: offset, access_type: 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(lock: &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 | mec_emi_base = base; |
146 | mec_emi_end = end; |
147 | } |
148 | EXPORT_SYMBOL(cros_ec_lpc_mec_init); |
149 | |