1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Chromium OS cros_ec driver - SPI interface
4 *
5 * Copyright (c) 2012 The Chromium OS Authors.
6 */
7
8/*
9 * The Matrix Keyboard Protocol driver handles talking to the keyboard
10 * controller chip. Mostly this is for keyboard functions, but some other
11 * things have slipped in, so we provide generic services to talk to the
12 * KBC.
13 */
14
15#include <common.h>
16#include <cros_ec.h>
17#include <dm.h>
18#include <errno.h>
19#include <log.h>
20#include <spi.h>
21
22int cros_ec_spi_packet(struct udevice *udev, int out_bytes, int in_bytes)
23{
24	struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
25	struct spi_slave *slave = dev_get_parent_priv(dev->dev);
26	ulong start;
27	uint8_t byte;
28	int rv;
29
30	/* Do the transfer */
31	if (spi_claim_bus(slave)) {
32		debug("%s: Cannot claim SPI bus\n", __func__);
33		return -1;
34	}
35
36	rv = spi_xfer(slave, out_bytes * 8, dev->dout, NULL, SPI_XFER_BEGIN);
37	if (rv)
38		goto done;
39	start = get_timer(0);
40	while (1) {
41		rv = spi_xfer(slave, 8, NULL, &byte, 0);
42		if (byte == SPI_PREAMBLE_END_BYTE)
43			break;
44		if (rv)
45			goto done;
46		if (get_timer(start) > 100) {
47			rv = -ETIMEDOUT;
48			goto done;
49		}
50	}
51
52	rv = spi_xfer(slave, in_bytes * 8, NULL, dev->din, 0);
53done:
54	spi_xfer(slave, 0, NULL, NULL, SPI_XFER_END);
55	spi_release_bus(slave);
56
57	if (rv) {
58		debug("%s: Cannot complete SPI transfer\n", __func__);
59		return -1;
60	}
61
62	return in_bytes;
63}
64
65/**
66 * Send a command to a LPC CROS_EC device and return the reply.
67 *
68 * The device's internal input/output buffers are used.
69 *
70 * @param dev		CROS_EC device
71 * @param cmd		Command to send (EC_CMD_...)
72 * @param cmd_version	Version of command to send (EC_VER_...)
73 * @param dout		Output data (may be NULL If dout_len=0)
74 * @param dout_len      Size of output data in bytes
75 * @param dinp		Returns pointer to response data. This will be
76 *			untouched unless we return a value > 0.
77 * @param din_len	Maximum size of response in bytes
78 * Return: number of bytes in response, or -1 on error
79 */
80int cros_ec_spi_command(struct udevice *udev, uint8_t cmd, int cmd_version,
81		     const uint8_t *dout, int dout_len,
82		     uint8_t **dinp, int din_len)
83{
84	struct cros_ec_dev *dev = dev_get_uclass_priv(udev);
85	struct spi_slave *slave = dev_get_parent_priv(dev->dev);
86	int in_bytes = din_len + 4;	/* status, length, checksum, trailer */
87	uint8_t *out;
88	uint8_t *p;
89	int csum, len;
90	int rv;
91
92	if (dev->protocol_version != 2) {
93		debug("%s: Unsupported EC protcol version %d\n",
94		      __func__, dev->protocol_version);
95		return -1;
96	}
97
98	/*
99	 * Sanity-check input size to make sure it plus transaction overhead
100	 * fits in the internal device buffer.
101	 */
102	if (in_bytes > sizeof(dev->din)) {
103		debug("%s: Cannot receive %d bytes\n", __func__, din_len);
104		return -1;
105	}
106
107	/* We represent message length as a byte */
108	if (dout_len > 0xff) {
109		debug("%s: Cannot send %d bytes\n", __func__, dout_len);
110		return -1;
111	}
112
113	/*
114	 * Clear input buffer so we don't get false hits for MSG_HEADER
115	 */
116	memset(dev->din, '\0', in_bytes);
117
118	if (spi_claim_bus(slave)) {
119		debug("%s: Cannot claim SPI bus\n", __func__);
120		return -1;
121	}
122
123	out = dev->dout;
124	out[0] = EC_CMD_VERSION0 + cmd_version;
125	out[1] = cmd;
126	out[2] = (uint8_t)dout_len;
127	memcpy(out + 3, dout, dout_len);
128	csum = cros_ec_calc_checksum(out, 3)
129	       + cros_ec_calc_checksum(dout, dout_len);
130	out[3 + dout_len] = (uint8_t)csum;
131
132	/*
133	 * Send output data and receive input data starting such that the
134	 * message body will be dword aligned.
135	 */
136	p = dev->din + sizeof(int64_t) - 2;
137	len = dout_len + 4;
138	cros_ec_dump_data("out", cmd, out, len);
139	rv = spi_xfer(slave, max(len, in_bytes) * 8, out, p,
140		      SPI_XFER_BEGIN | SPI_XFER_END);
141
142	spi_release_bus(slave);
143
144	if (rv) {
145		debug("%s: Cannot complete SPI transfer\n", __func__);
146		return -1;
147	}
148
149	len = min((int)p[1], din_len);
150	cros_ec_dump_data("in", -1, p, len + 3);
151
152	/* Response code is first byte of message */
153	if (p[0] != EC_RES_SUCCESS) {
154		log_debug("Returned status %d\n", p[0]);
155		return -(int)(p[0]);
156	}
157
158	/* Check checksum */
159	csum = cros_ec_calc_checksum(p, len + 2);
160	if (csum != p[len + 2]) {
161		debug("%s: Invalid checksum rx %#02x, calced %#02x\n", __func__,
162		      p[2 + len], csum);
163		return -1;
164	}
165
166	/* Anything else is the response data */
167	*dinp = p + 2;
168
169	return len;
170}
171
172static int cros_ec_probe(struct udevice *dev)
173{
174	return cros_ec_register(dev);
175}
176
177static struct dm_cros_ec_ops cros_ec_ops = {
178	.packet = cros_ec_spi_packet,
179	.command = cros_ec_spi_command,
180};
181
182static const struct udevice_id cros_ec_ids[] = {
183	{ .compatible = "google,cros-ec-spi" },
184	{ }
185};
186
187U_BOOT_DRIVER(google_cros_ec_spi) = {
188	.name		= "google_cros_ec_spi",
189	.id		= UCLASS_CROS_EC,
190	.of_match	= cros_ec_ids,
191	.probe		= cros_ec_probe,
192	.ops		= &cros_ec_ops,
193};
194