1/*
  2 * Driver for the Diolan DLN-2 USB-I2C adapter
  3 *
  4 * Copyright (c) 2014 Intel Corporation
  5 *
  6 * Derived from:
  7 *  i2c-diolan-u2c.c
  8 *  Copyright (c) 2010-2011 Ericsson AB
  9 *
 10 * This program is free software; you can redistribute it and/or
 11 * modify it under the terms of the GNU General Public License as
 12 * published by the Free Software Foundation, version 2.
 13 */
 14
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/types.h>
 18#include <linux/slab.h>
 19#include <linux/i2c.h>
 20#include <linux/platform_device.h>
 21#include <linux/mfd/dln2.h>
 22#include <linux/acpi.h>
 23
 24#define DLN2_I2C_MODULE_ID		0x03
 25#define DLN2_I2C_CMD(cmd)		DLN2_CMD(cmd, DLN2_I2C_MODULE_ID)
 26
 27/* I2C commands */
 28#define DLN2_I2C_GET_PORT_COUNT		DLN2_I2C_CMD(0x00)
 29#define DLN2_I2C_ENABLE			DLN2_I2C_CMD(0x01)
 30#define DLN2_I2C_DISABLE		DLN2_I2C_CMD(0x02)
 31#define DLN2_I2C_IS_ENABLED		DLN2_I2C_CMD(0x03)
 32#define DLN2_I2C_WRITE			DLN2_I2C_CMD(0x06)
 33#define DLN2_I2C_READ			DLN2_I2C_CMD(0x07)
 34#define DLN2_I2C_SCAN_DEVICES		DLN2_I2C_CMD(0x08)
 35#define DLN2_I2C_PULLUP_ENABLE		DLN2_I2C_CMD(0x09)
 36#define DLN2_I2C_PULLUP_DISABLE		DLN2_I2C_CMD(0x0A)
 37#define DLN2_I2C_PULLUP_IS_ENABLED	DLN2_I2C_CMD(0x0B)
 38#define DLN2_I2C_TRANSFER		DLN2_I2C_CMD(0x0C)
 39#define DLN2_I2C_SET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0D)
 40#define DLN2_I2C_GET_MAX_REPLY_COUNT	DLN2_I2C_CMD(0x0E)
 41
 42#define DLN2_I2C_MAX_XFER_SIZE		256
 43#define DLN2_I2C_BUF_SIZE		(DLN2_I2C_MAX_XFER_SIZE + 16)
 44
 45struct dln2_i2c {
 46	struct platform_device *pdev;
 47	struct i2c_adapter adapter;
 48	u8 port;
 49	/*
 50	 * Buffer to hold the packet for read or write transfers. One is enough
 51	 * since we can't have multiple transfers in parallel on the i2c bus.
 52	 */
 53	void *buf;
 54};
 55
 56static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
 57{
 58	u16 cmd;
 59	struct {
 60		u8 port;
 61	} tx;
 62
 63	tx.port = dln2->port;
 64
 65	if (enable)
 66		cmd = DLN2_I2C_ENABLE;
 67	else
 68		cmd = DLN2_I2C_DISABLE;
 69
 70	return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
 71}
 72
 73static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
 74			  u8 *data, u16 data_len)
 75{
 76	int ret;
 77	struct {
 78		u8 port;
 79		u8 addr;
 80		u8 mem_addr_len;
 81		__le32 mem_addr;
 82		__le16 buf_len;
 83		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
 84	} __packed *tx = dln2->buf;
 85	unsigned len;
 86
 87	BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);
 88
 89	tx->port = dln2->port;
 90	tx->addr = addr;
 91	tx->mem_addr_len = 0;
 92	tx->mem_addr = 0;
 93	tx->buf_len = cpu_to_le16(data_len);
 94	memcpy(tx->buf, data, data_len);
 95
 96	len = sizeof(*tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
 97	ret = dln2_transfer_tx(dln2->pdev, DLN2_I2C_WRITE, tx, len);
 98	if (ret < 0)
 99		return ret;
100
101	return data_len;
102}
103
104static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
105			 u16 data_len)
106{
107	int ret;
108	struct {
109		u8 port;
110		u8 addr;
111		u8 mem_addr_len;
112		__le32 mem_addr;
113		__le16 buf_len;
114	} __packed tx;
115	struct {
116		__le16 buf_len;
117		u8 buf[DLN2_I2C_MAX_XFER_SIZE];
118	} __packed *rx = dln2->buf;
119	unsigned rx_len = sizeof(*rx);
120
121	BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);
122
123	tx.port = dln2->port;
124	tx.addr = addr;
125	tx.mem_addr_len = 0;
126	tx.mem_addr = 0;
127	tx.buf_len = cpu_to_le16(data_len);
128
129	ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
130			    rx, &rx_len);
131	if (ret < 0)
132		return ret;
133	if (rx_len < sizeof(rx->buf_len) + data_len)
134		return -EPROTO;
135	if (le16_to_cpu(rx->buf_len) != data_len)
136		return -EPROTO;
137
138	memcpy(data, rx->buf, data_len);
139
140	return data_len;
141}
142
143static int dln2_i2c_xfer(struct i2c_adapter *adapter,
144			 struct i2c_msg *msgs, int num)
145{
146	struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
147	struct i2c_msg *pmsg;
148	int i;
149
150	for (i = 0; i < num; i++) {
151		int ret;
152
153		pmsg = &msgs[i];
154
155		if (pmsg->flags & I2C_M_RD) {
156			ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
157					    pmsg->len);
158			if (ret < 0)
159				return ret;
160
161			pmsg->len = ret;
162		} else {
163			ret = dln2_i2c_write(dln2, pmsg->addr, pmsg->buf,
164					     pmsg->len);
165			if (ret != pmsg->len)
166				return -EPROTO;
167		}
168	}
169
170	return num;
171}
172
173static u32 dln2_i2c_func(struct i2c_adapter *a)
174{
175	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
176		I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
177		I2C_FUNC_SMBUS_I2C_BLOCK;
178}
179
180static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
181	.master_xfer = dln2_i2c_xfer,
182	.functionality = dln2_i2c_func,
183};
184
185static const struct i2c_adapter_quirks dln2_i2c_quirks = {
186	.max_read_len = DLN2_I2C_MAX_XFER_SIZE,
187	.max_write_len = DLN2_I2C_MAX_XFER_SIZE,
188};
189
190static int dln2_i2c_probe(struct platform_device *pdev)
191{
192	int ret;
193	struct dln2_i2c *dln2;
194	struct device *dev = &pdev->dev;
195	struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);
196
197	dln2 = devm_kzalloc(dev, sizeof(*dln2), GFP_KERNEL);
198	if (!dln2)
199		return -ENOMEM;
200
201	dln2->buf = devm_kmalloc(dev, DLN2_I2C_BUF_SIZE, GFP_KERNEL);
202	if (!dln2->buf)
203		return -ENOMEM;
204
205	dln2->pdev = pdev;
206	dln2->port = pdata->port;
207
208	/* setup i2c adapter description */
209	dln2->adapter.owner = THIS_MODULE;
210	dln2->adapter.class = I2C_CLASS_HWMON;
211	dln2->adapter.algo = &dln2_i2c_usb_algorithm;
212	dln2->adapter.quirks = &dln2_i2c_quirks;
213	dln2->adapter.dev.parent = dev;
214	ACPI_COMPANION_SET(&dln2->adapter.dev, ACPI_COMPANION(&pdev->dev));
215	dln2->adapter.dev.of_node = dev->of_node;
216	i2c_set_adapdata(&dln2->adapter, dln2);
217	snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
218		 "dln2-i2c", dev_name(pdev->dev.parent), dln2->port);
219
220	platform_set_drvdata(pdev, dln2);
221
222	/* initialize the i2c interface */
223	ret = dln2_i2c_enable(dln2, true);
224	if (ret < 0) {
225		dev_err(dev, "failed to initialize adapter: %d\n", ret);
226		return ret;
227	}
228
229	/* and finally attach to i2c layer */
230	ret = i2c_add_adapter(&dln2->adapter);
231	if (ret < 0)
232		goto out_disable;
233
234	return 0;
235
236out_disable:
237	dln2_i2c_enable(dln2, false);
238
239	return ret;
240}
241
242static int dln2_i2c_remove(struct platform_device *pdev)
243{
244	struct dln2_i2c *dln2 = platform_get_drvdata(pdev);
245
246	i2c_del_adapter(&dln2->adapter);
247	dln2_i2c_enable(dln2, false);
248
249	return 0;
250}
251
252static struct platform_driver dln2_i2c_driver = {
253	.driver.name	= "dln2-i2c",
254	.probe		= dln2_i2c_probe,
255	.remove		= dln2_i2c_remove,
256};
257
258module_platform_driver(dln2_i2c_driver);
259
260MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
261MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C master interface");
262MODULE_LICENSE("GPL v2");
263MODULE_ALIAS("platform:dln2-i2c");