1 /*
2 * cros_ec_lpc_reg - LPC access to the Chrome OS Embedded Controller
3 *
4 * Copyright (C) 2016 Google, Inc
5 *
6 * This software is licensed under the terms of the GNU General Public
7 * License version 2, as published by the Free Software Foundation, and
8 * may be copied, distributed, and modified under those terms.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * This driver uses the Chrome OS EC byte-level message-based protocol for
16 * communicating the keyboard state (which keys are pressed) from a keyboard EC
17 * to the AP over some bus (such as i2c, lpc, spi). The EC does debouncing,
18 * but everything else (including deghosting) is done here. The main
19 * motivation for this is to keep the EC firmware as simple as possible, since
20 * it cannot be easily upgraded and EC flash/IRAM space is relatively
21 * expensive.
22 */
23
24 #include <linux/io.h>
25 #include <linux/mfd/cros_ec.h>
26 #include <linux/mfd/cros_ec_commands.h>
27 #include <linux/mfd/cros_ec_lpc_mec.h>
28
lpc_read_bytes(unsigned int offset,unsigned int length,u8 * dest)29 static u8 lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
30 {
31 int i;
32 int sum = 0;
33
34 for (i = 0; i < length; ++i) {
35 dest[i] = inb(offset + i);
36 sum += dest[i];
37 }
38
39 /* Return checksum of all bytes read */
40 return sum;
41 }
42
lpc_write_bytes(unsigned int offset,unsigned int length,u8 * msg)43 static u8 lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
44 {
45 int i;
46 int sum = 0;
47
48 for (i = 0; i < length; ++i) {
49 outb(msg[i], offset + i);
50 sum += msg[i];
51 }
52
53 /* Return checksum of all bytes written */
54 return sum;
55 }
56
57 #ifdef CONFIG_CROS_EC_LPC_MEC
58
cros_ec_lpc_read_bytes(unsigned int offset,unsigned int length,u8 * dest)59 u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
60 {
61 if (length == 0)
62 return 0;
63
64 /* Access desired range through EMI interface */
65 if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
66 /* Ensure we don't straddle EMI region */
67 if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
68 return 0;
69
70 return cros_ec_lpc_io_bytes_mec(MEC_IO_READ, offset, length,
71 dest);
72 }
73
74 if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
75 offset < MEC_EMI_RANGE_START))
76 return 0;
77
78 return lpc_read_bytes(offset, length, dest);
79 }
80
cros_ec_lpc_write_bytes(unsigned int offset,unsigned int length,u8 * msg)81 u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
82 {
83 if (length == 0)
84 return 0;
85
86 /* Access desired range through EMI interface */
87 if (offset >= MEC_EMI_RANGE_START && offset <= MEC_EMI_RANGE_END) {
88 /* Ensure we don't straddle EMI region */
89 if (WARN_ON(offset + length - 1 > MEC_EMI_RANGE_END))
90 return 0;
91
92 return cros_ec_lpc_io_bytes_mec(MEC_IO_WRITE, offset, length,
93 msg);
94 }
95
96 if (WARN_ON(offset + length > MEC_EMI_RANGE_START &&
97 offset < MEC_EMI_RANGE_START))
98 return 0;
99
100 return lpc_write_bytes(offset, length, msg);
101 }
102
cros_ec_lpc_reg_init(void)103 void cros_ec_lpc_reg_init(void)
104 {
105 cros_ec_lpc_mec_init();
106 }
107
cros_ec_lpc_reg_destroy(void)108 void cros_ec_lpc_reg_destroy(void)
109 {
110 cros_ec_lpc_mec_destroy();
111 }
112
113 #else /* CONFIG_CROS_EC_LPC_MEC */
114
cros_ec_lpc_read_bytes(unsigned int offset,unsigned int length,u8 * dest)115 u8 cros_ec_lpc_read_bytes(unsigned int offset, unsigned int length, u8 *dest)
116 {
117 return lpc_read_bytes(offset, length, dest);
118 }
119
cros_ec_lpc_write_bytes(unsigned int offset,unsigned int length,u8 * msg)120 u8 cros_ec_lpc_write_bytes(unsigned int offset, unsigned int length, u8 *msg)
121 {
122 return lpc_write_bytes(offset, length, msg);
123 }
124
cros_ec_lpc_reg_init(void)125 void cros_ec_lpc_reg_init(void)
126 {
127 }
128
cros_ec_lpc_reg_destroy(void)129 void cros_ec_lpc_reg_destroy(void)
130 {
131 }
132
133 #endif /* CONFIG_CROS_EC_LPC_MEC */
134