summaryrefslogtreecommitdiffstats
path: root/drivers/i2c/busses/i2c-designware-slave.c
blob: 2e079cf20bb5b40c09004bdc02a8124352fab958 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
// SPDX-License-Identifier: GPL-2.0
/*
 * Synopsys DesignWare I2C adapter driver (slave only).
 *
 * Based on the Synopsys DesignWare I2C adapter driver (master).
 *
 * Copyright (C) 2016 Synopsys Inc.
 */
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>

#include "i2c-designware-core.h"

static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
{
	/* Configure Tx/Rx FIFO threshold levels. */
	regmap_write(dev->map, DW_IC_TX_TL, 0);
	regmap_write(dev->map, DW_IC_RX_TL, 0);

	/* Configure the I2C slave. */
	regmap_write(dev->map, DW_IC_CON, dev->slave_cfg);
	regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK);
}

/**
 * i2c_dw_init_slave() - Initialize the designware i2c slave hardware
 * @dev: device private data
 *
 * This function configures and enables the I2C in slave mode.
 * This function is called during I2C init function, and in case of timeout at
 * run time.
 */
static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
{
	int ret;

	ret = i2c_dw_acquire_lock(dev);
	if (ret)
		return ret;

	/* Disable the adapter. */
	__i2c_dw_disable(dev);

	/* Write SDA hold time if supported */
	if (dev->sda_hold_time)
		regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);

	i2c_dw_configure_fifo_slave(dev);
	i2c_dw_release_lock(dev);

	return 0;
}

static int i2c_dw_reg_slave(struct i2c_client *slave)
{
	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

	if (dev->slave)
		return -EBUSY;
	if (slave->flags & I2C_CLIENT_TEN)
		return -EAFNOSUPPORT;
	pm_runtime_get_sync(dev->dev);

	/*
	 * Set slave address in the IC_SAR register,
	 * the address to which the DW_apb_i2c responds.
	 */
	__i2c_dw_disable_nowait(dev);
	regmap_write(dev->map, DW_IC_SAR, slave->addr);
	dev->slave = slave;

	__i2c_dw_enable(dev);

	dev->status = 0;

	return 0;
}

static int i2c_dw_unreg_slave(struct i2c_client *slave)
{
	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);

	regmap_write(dev->map, DW_IC_INTR_MASK, 0);
	dev->disable(dev);
	synchronize_irq(dev->irq);
	dev->slave = NULL;
	pm_runtime_put(dev->dev);

	return 0;
}

static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
{
	unsigned int stat, dummy;

	/*
	 * The IC_INTR_STAT register just indicates "enabled" interrupts.
	 * The unmasked raw version of interrupt status bits is available
	 * in the IC_RAW_INTR_STAT register.
	 *
	 * That is,
	 *   stat = readl(IC_INTR_STAT);
	 * equals to,
	 *   stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
	 *
	 * The raw version might be useful for debugging purposes.
	 */
	regmap_read(dev->map, DW_IC_INTR_STAT, &stat);

	/*
	 * Do not use the IC_CLR_INTR register to clear interrupts, or
	 * you'll miss some interrupts, triggered during the period from
	 * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
	 *
	 * Instead, use the separately-prepared IC_CLR_* registers.
	 */
	if (stat & DW_IC_INTR_TX_ABRT)
		regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
	if (stat & DW_IC_INTR_RX_UNDER)
		regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
	if (stat & DW_IC_INTR_RX_OVER)
		regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
	if (stat & DW_IC_INTR_TX_OVER)
		regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
	if (stat & DW_IC_INTR_RX_DONE)
		regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
	if (stat & DW_IC_INTR_ACTIVITY)
		regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
	if (stat & DW_IC_INTR_STOP_DET)
		regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
	if (stat & DW_IC_INTR_START_DET)
		regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
	if (stat & DW_IC_INTR_GEN_CALL)
		regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);

	return stat;
}

/*
 * Interrupt service routine. This gets called whenever an I2C slave interrupt
 * occurs.
 */
static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
{
	struct dw_i2c_dev *dev = dev_id;
	unsigned int raw_stat, stat, enabled, tmp;
	u8 val = 0, slave_activity;

	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
	regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
	regmap_read(dev->map, DW_IC_STATUS, &tmp);
	slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);

	if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
		return IRQ_NONE;

	stat = i2c_dw_read_clear_intrbits_slave(dev);
	dev_dbg(dev->dev,
		"%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
		enabled, slave_activity, raw_stat, stat);

	if (stat & DW_IC_INTR_RX_FULL) {
		if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) {
			dev->status |= STATUS_WRITE_IN_PROGRESS;
			dev->status &= ~STATUS_READ_IN_PROGRESS;
			i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
					&val);
		}

		do {
			regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
			if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE)
				i2c_slave_event(dev->slave,
						I2C_SLAVE_WRITE_REQUESTED,
						&val);
			val = tmp;
			i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
					&val);
			regmap_read(dev->map, DW_IC_STATUS, &tmp);
		} while (tmp & DW_IC_STATUS_RFNE);
	}

	if (stat & DW_IC_INTR_RD_REQ) {
		if (slave_activity) {
			regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);

			if (!(dev->status & STATUS_READ_IN_PROGRESS)) {
				i2c_slave_event(dev->slave,
						I2C_SLAVE_READ_REQUESTED,
						&val);
				dev->status |= STATUS_READ_IN_PROGRESS;
				dev->status &= ~STATUS_WRITE_IN_PROGRESS;
			} else {
				i2c_slave_event(dev->slave,
						I2C_SLAVE_READ_PROCESSED,
						&val);
			}
			regmap_write(dev->map, DW_IC_DATA_CMD, val);
		}
	}

	if (stat & DW_IC_INTR_STOP_DET)
		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);

	return IRQ_HANDLED;
}

static const struct i2c_algorithm i2c_dw_algo = {
	.functionality = i2c_dw_func,
	.reg_slave = i2c_dw_reg_slave,
	.unreg_slave = i2c_dw_unreg_slave,
};

void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
{
	dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY;

	dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL |
			 DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED;

	dev->mode = DW_IC_SLAVE;
}
EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);

int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
{
	struct i2c_adapter *adap = &dev->adapter;
	int ret;

	dev->init = i2c_dw_init_slave;
	dev->disable = i2c_dw_disable;

	ret = i2c_dw_init_regmap(dev);
	if (ret)
		return ret;

	ret = i2c_dw_set_sda_hold(dev);
	if (ret)
		return ret;

	ret = i2c_dw_set_fifo_size(dev);
	if (ret)
		return ret;

	ret = dev->init(dev);
	if (ret)
		return ret;

	snprintf(adap->name, sizeof(adap->name),
		 "Synopsys DesignWare I2C Slave adapter");
	adap->retries = 3;
	adap->algo = &i2c_dw_algo;
	adap->dev.parent = dev->dev;
	i2c_set_adapdata(adap, dev);

	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
			       IRQF_SHARED, dev_name(dev->dev), dev);
	if (ret) {
		dev_err(dev->dev, "failure requesting irq %i: %d\n",
			dev->irq, ret);
		return ret;
	}

	ret = i2c_add_numbered_adapter(adap);
	if (ret)
		dev_err(dev->dev, "failure adding adapter: %d\n", ret);

	return ret;
}
EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);

MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
MODULE_LICENSE("GPL v2");