1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * drivers/i2c/busses/i2c-tegra-bpmp.c
4 *
5 * Copyright (c) 2016 NVIDIA Corporation.  All rights reserved.
6 *
7 * Author: Shardar Shariff Md <smohammed@nvidia.com>
8 */
9
10#include <linux/err.h>
11#include <linux/i2c.h>
12#include <linux/init.h>
13#include <linux/kernel.h>
14#include <linux/module.h>
15#include <linux/of_device.h>
16#include <linux/platform_device.h>
17#include <linux/pm_runtime.h>
18
19#include <soc/tegra/bpmp-abi.h>
20#include <soc/tegra/bpmp.h>
21
22/*
23 * Serialized I2C message header size is 6 bytes and includes address, flags
24 * and length
25 */
26#define SERIALI2C_HDR_SIZE 6
27
28struct tegra_bpmp_i2c {
29	struct i2c_adapter adapter;
30	struct device *dev;
31
32	struct tegra_bpmp *bpmp;
33	unsigned int bus;
34};
35
36/*
37 * Linux flags are translated to BPMP defined I2C flags that are used in BPMP
38 * firmware I2C driver to avoid any issues in future if Linux I2C flags are
39 * changed.
40 */
41static int tegra_bpmp_xlate_flags(u16 flags, u16 *out)
42{
43	if (flags & I2C_M_TEN) {
44		*out |= SERIALI2C_TEN;
45		flags &= ~I2C_M_TEN;
46	}
47
48	if (flags & I2C_M_RD) {
49		*out |= SERIALI2C_RD;
50		flags &= ~I2C_M_RD;
51	}
52
53	if (flags & I2C_M_STOP) {
54		*out |= SERIALI2C_STOP;
55		flags &= ~I2C_M_STOP;
56	}
57
58	if (flags & I2C_M_NOSTART) {
59		*out |= SERIALI2C_NOSTART;
60		flags &= ~I2C_M_NOSTART;
61	}
62
63	if (flags & I2C_M_REV_DIR_ADDR) {
64		*out |= SERIALI2C_REV_DIR_ADDR;
65		flags &= ~I2C_M_REV_DIR_ADDR;
66	}
67
68	if (flags & I2C_M_IGNORE_NAK) {
69		*out |= SERIALI2C_IGNORE_NAK;
70		flags &= ~I2C_M_IGNORE_NAK;
71	}
72
73	if (flags & I2C_M_NO_RD_ACK) {
74		*out |= SERIALI2C_NO_RD_ACK;
75		flags &= ~I2C_M_NO_RD_ACK;
76	}
77
78	if (flags & I2C_M_RECV_LEN) {
79		*out |= SERIALI2C_RECV_LEN;
80		flags &= ~I2C_M_RECV_LEN;
81	}
82
83	return 0;
84}
85
86/**
87 * The serialized I2C format is simply the following:
88 * [addr little-endian][flags little-endian][len little-endian][data if write]
89 * [addr little-endian][flags little-endian][len little-endian][data if write]
90 *  ...
91 *
92 * The flags are translated from Linux kernel representation to seriali2c
93 * representation. Any undefined flag being set causes an error.
94 *
95 * The data is there only for writes. Reads have the data transferred in the
96 * other direction, and thus data is not present.
97 *
98 * See deserialize_i2c documentation for the data format in the other direction.
99 */
100static int tegra_bpmp_serialize_i2c_msg(struct tegra_bpmp_i2c *i2c,
101					struct mrq_i2c_request *request,
102					struct i2c_msg *msgs,
103					unsigned int num)
104{
105	char *buf = request->xfer.data_buf;
106	unsigned int i, j, pos = 0;
107	int err;
108
109	for (i = 0; i < num; i++) {
110		struct i2c_msg *msg = &msgs[i];
111		u16 flags = 0;
112
113		err = tegra_bpmp_xlate_flags(msg->flags, &flags);
114		if (err < 0)
115			return err;
116
117		buf[pos++] = msg->addr & 0xff;
118		buf[pos++] = (msg->addr & 0xff00) >> 8;
119		buf[pos++] = flags & 0xff;
120		buf[pos++] = (flags & 0xff00) >> 8;
121		buf[pos++] = msg->len & 0xff;
122		buf[pos++] = (msg->len & 0xff00) >> 8;
123
124		if ((flags & SERIALI2C_RD) == 0) {
125			for (j = 0; j < msg->len; j++)
126				buf[pos++] = msg->buf[j];
127		}
128	}
129
130	request->xfer.data_size = pos;
131
132	return 0;
133}
134
135/**
136 * The data in the BPMP -> CPU direction is composed of sequential blocks for
137 * those messages that have I2C_M_RD. So, for example, if you have:
138 *
139 * - !I2C_M_RD, len == 5, data == a0 01 02 03 04
140 * - !I2C_M_RD, len == 1, data == a0
141 * - I2C_M_RD, len == 2, data == [uninitialized buffer 1]
142 * - !I2C_M_RD, len == 1, data == a2
143 * - I2C_M_RD, len == 2, data == [uninitialized buffer 2]
144 *
145 * ...then the data in the BPMP -> CPU direction would be 4 bytes total, and
146 * would contain 2 bytes that will go to uninitialized buffer 1, and 2 bytes
147 * that will go to uninitialized buffer 2.
148 */
149static int tegra_bpmp_i2c_deserialize(struct tegra_bpmp_i2c *i2c,
150				      struct mrq_i2c_response *response,
151				      struct i2c_msg *msgs,
152				      unsigned int num)
153{
154	size_t size = response->xfer.data_size, len = 0, pos = 0;
155	char *buf = response->xfer.data_buf;
156	unsigned int i;
157
158	for (i = 0; i < num; i++)
159		if (msgs[i].flags & I2C_M_RD)
160			len += msgs[i].len;
161
162	if (len != size)
163		return -EINVAL;
164
165	for (i = 0; i < num; i++) {
166		if (msgs[i].flags & I2C_M_RD) {
167			memcpy(msgs[i].buf, buf + pos, msgs[i].len);
168			pos += msgs[i].len;
169		}
170	}
171
172	return 0;
173}
174
175static int tegra_bpmp_i2c_msg_len_check(struct i2c_msg *msgs, unsigned int num)
176{
177	size_t tx_len = 0, rx_len = 0;
178	unsigned int i;
179
180	for (i = 0; i < num; i++)
181		if (!(msgs[i].flags & I2C_M_RD))
182			tx_len += SERIALI2C_HDR_SIZE + msgs[i].len;
183
184	if (tx_len > TEGRA_I2C_IPC_MAX_IN_BUF_SIZE)
185		return -EINVAL;
186
187	for (i = 0; i < num; i++)
188		if ((msgs[i].flags & I2C_M_RD))
189			rx_len += msgs[i].len;
190
191	if (rx_len > TEGRA_I2C_IPC_MAX_OUT_BUF_SIZE)
192		return -EINVAL;
193
194	return 0;
195}
196
197static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
198				   struct mrq_i2c_request *request,
199				   struct mrq_i2c_response *response,
200				   bool atomic)
201{
202	struct tegra_bpmp_message msg;
203	int err;
204
205	request->cmd = CMD_I2C_XFER;
206	request->xfer.bus_id = i2c->bus;
207
208	memset(&msg, 0, sizeof(msg));
209	msg.mrq = MRQ_I2C;
210	msg.tx.data = request;
211	msg.tx.size = sizeof(*request);
212	msg.rx.data = response;
213	msg.rx.size = sizeof(*response);
214
215	if (atomic)
216		err = tegra_bpmp_transfer_atomic(i2c->bpmp, &msg);
217	else
218		err = tegra_bpmp_transfer(i2c->bpmp, &msg);
219
220	return err;
221}
222
223static int tegra_bpmp_i2c_xfer_common(struct i2c_adapter *adapter,
224				      struct i2c_msg *msgs, int num,
225				      bool atomic)
226{
227	struct tegra_bpmp_i2c *i2c = i2c_get_adapdata(adapter);
228	struct mrq_i2c_response response;
229	struct mrq_i2c_request request;
230	int err;
231
232	err = tegra_bpmp_i2c_msg_len_check(msgs, num);
233	if (err < 0) {
234		dev_err(i2c->dev, "unsupported message length\n");
235		return err;
236	}
237
238	memset(&request, 0, sizeof(request));
239	memset(&response, 0, sizeof(response));
240
241	err = tegra_bpmp_serialize_i2c_msg(i2c, &request, msgs, num);
242	if (err < 0) {
243		dev_err(i2c->dev, "failed to serialize message: %d\n", err);
244		return err;
245	}
246
247	err = tegra_bpmp_i2c_msg_xfer(i2c, &request, &response, atomic);
248	if (err < 0) {
249		dev_err(i2c->dev, "failed to transfer message: %d\n", err);
250		return err;
251	}
252
253	err = tegra_bpmp_i2c_deserialize(i2c, &response, msgs, num);
254	if (err < 0) {
255		dev_err(i2c->dev, "failed to deserialize message: %d\n", err);
256		return err;
257	}
258
259	return num;
260}
261
262static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
263			       struct i2c_msg *msgs, int num)
264{
265	return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, false);
266}
267
268static int tegra_bpmp_i2c_xfer_atomic(struct i2c_adapter *adapter,
269				      struct i2c_msg *msgs, int num)
270{
271	return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, true);
272}
273
274static u32 tegra_bpmp_i2c_func(struct i2c_adapter *adapter)
275{
276	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
277	       I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_NOSTART;
278}
279
280static const struct i2c_algorithm tegra_bpmp_i2c_algo = {
281	.master_xfer = tegra_bpmp_i2c_xfer,
282	.master_xfer_atomic = tegra_bpmp_i2c_xfer_atomic,
283	.functionality = tegra_bpmp_i2c_func,
284};
285
286static int tegra_bpmp_i2c_probe(struct platform_device *pdev)
287{
288	struct tegra_bpmp_i2c *i2c;
289	u32 value;
290	int err;
291
292	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
293	if (!i2c)
294		return -ENOMEM;
295
296	i2c->dev = &pdev->dev;
297
298	i2c->bpmp = dev_get_drvdata(pdev->dev.parent);
299	if (!i2c->bpmp)
300		return -ENODEV;
301
302	err = of_property_read_u32(pdev->dev.of_node, "nvidia,bpmp-bus-id",
303				   &value);
304	if (err < 0)
305		return err;
306
307	i2c->bus = value;
308
309	i2c_set_adapdata(&i2c->adapter, i2c);
310	i2c->adapter.owner = THIS_MODULE;
311	strlcpy(i2c->adapter.name, "Tegra BPMP I2C adapter",
312		sizeof(i2c->adapter.name));
313	i2c->adapter.algo = &tegra_bpmp_i2c_algo;
314	i2c->adapter.dev.parent = &pdev->dev;
315	i2c->adapter.dev.of_node = pdev->dev.of_node;
316
317	platform_set_drvdata(pdev, i2c);
318
319	return i2c_add_adapter(&i2c->adapter);
320}
321
322static int tegra_bpmp_i2c_remove(struct platform_device *pdev)
323{
324	struct tegra_bpmp_i2c *i2c = platform_get_drvdata(pdev);
325
326	i2c_del_adapter(&i2c->adapter);
327
328	return 0;
329}
330
331static const struct of_device_id tegra_bpmp_i2c_of_match[] = {
332	{ .compatible = "nvidia,tegra186-bpmp-i2c", },
333	{ }
334};
335MODULE_DEVICE_TABLE(of, tegra_bpmp_i2c_of_match);
336
337static struct platform_driver tegra_bpmp_i2c_driver = {
338	.driver = {
339		.name = "tegra-bpmp-i2c",
340		.of_match_table = tegra_bpmp_i2c_of_match,
341	},
342	.probe = tegra_bpmp_i2c_probe,
343	.remove = tegra_bpmp_i2c_remove,
344};
345module_platform_driver(tegra_bpmp_i2c_driver);
346
347MODULE_DESCRIPTION("NVIDIA Tegra BPMP I2C bus controller driver");
348MODULE_AUTHOR("Shardar Shariff Md <smohammed@nvidia.com>");
349MODULE_AUTHOR("Juha-Matti Tilli");
350MODULE_LICENSE("GPL v2");
351