1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Synopsys DesignWare I2C adapter driver (slave only).
4 *
5 * Based on the Synopsys DesignWare I2C adapter driver (master).
6 *
7 * Copyright (C) 2016 Synopsys Inc.
8 */
9
10 #define DEFAULT_SYMBOL_NAMESPACE "I2C_DW"
11
12 #include <linux/delay.h>
13 #include <linux/err.h>
14 #include <linux/errno.h>
15 #include <linux/i2c.h>
16 #include <linux/interrupt.h>
17 #include <linux/io.h>
18 #include <linux/module.h>
19 #include <linux/pm_runtime.h>
20 #include <linux/regmap.h>
21
22 #include "i2c-designware-core.h"
23
i2c_dw_configure_fifo_slave(struct dw_i2c_dev * dev)24 static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
25 {
26 /* Configure Tx/Rx FIFO threshold levels. */
27 regmap_write(dev->map, DW_IC_TX_TL, 0);
28 regmap_write(dev->map, DW_IC_RX_TL, 0);
29
30 /* Configure the I2C slave. */
31 regmap_write(dev->map, DW_IC_CON, dev->slave_cfg);
32 regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK);
33 }
34
35 /**
36 * i2c_dw_init_slave() - Initialize the DesignWare i2c slave hardware
37 * @dev: device private data
38 *
39 * This function configures and enables the I2C in slave mode.
40 * This function is called during I2C init function, and in case of timeout at
41 * run time.
42 *
43 * Return: 0 on success, or negative errno otherwise.
44 */
i2c_dw_init_slave(struct dw_i2c_dev * dev)45 static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
46 {
47 int ret;
48
49 ret = i2c_dw_acquire_lock(dev);
50 if (ret)
51 return ret;
52
53 /* Disable the adapter. */
54 __i2c_dw_disable(dev);
55
56 /* Write SDA hold time if supported */
57 if (dev->sda_hold_time)
58 regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
59
60 i2c_dw_configure_fifo_slave(dev);
61 i2c_dw_release_lock(dev);
62
63 return 0;
64 }
65
i2c_dw_reg_slave(struct i2c_client * slave)66 static int i2c_dw_reg_slave(struct i2c_client *slave)
67 {
68 struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
69
70 if (dev->slave)
71 return -EBUSY;
72 if (slave->flags & I2C_CLIENT_TEN)
73 return -EAFNOSUPPORT;
74 pm_runtime_get_sync(dev->dev);
75
76 /*
77 * Set slave address in the IC_SAR register,
78 * the address to which the DW_apb_i2c responds.
79 */
80 __i2c_dw_disable_nowait(dev);
81 regmap_write(dev->map, DW_IC_SAR, slave->addr);
82 dev->slave = slave;
83
84 __i2c_dw_enable(dev);
85
86 dev->status = 0;
87
88 return 0;
89 }
90
i2c_dw_unreg_slave(struct i2c_client * slave)91 static int i2c_dw_unreg_slave(struct i2c_client *slave)
92 {
93 struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
94
95 regmap_write(dev->map, DW_IC_INTR_MASK, 0);
96 i2c_dw_disable(dev);
97 synchronize_irq(dev->irq);
98 dev->slave = NULL;
99 pm_runtime_put(dev->dev);
100
101 return 0;
102 }
103
i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev * dev)104 static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
105 {
106 unsigned int stat, dummy;
107
108 /*
109 * The IC_INTR_STAT register just indicates "enabled" interrupts.
110 * The unmasked raw version of interrupt status bits is available
111 * in the IC_RAW_INTR_STAT register.
112 *
113 * That is,
114 * stat = readl(IC_INTR_STAT);
115 * equals to,
116 * stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
117 *
118 * The raw version might be useful for debugging purposes.
119 */
120 regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
121
122 /*
123 * Do not use the IC_CLR_INTR register to clear interrupts, or
124 * you'll miss some interrupts, triggered during the period from
125 * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
126 *
127 * Instead, use the separately-prepared IC_CLR_* registers.
128 */
129 if (stat & DW_IC_INTR_TX_ABRT)
130 regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
131 if (stat & DW_IC_INTR_RX_UNDER)
132 regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
133 if (stat & DW_IC_INTR_RX_OVER)
134 regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
135 if (stat & DW_IC_INTR_TX_OVER)
136 regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
137 if (stat & DW_IC_INTR_RX_DONE)
138 regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
139 if (stat & DW_IC_INTR_ACTIVITY)
140 regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
141 if (stat & DW_IC_INTR_STOP_DET)
142 regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
143 if (stat & DW_IC_INTR_START_DET)
144 regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
145 if (stat & DW_IC_INTR_GEN_CALL)
146 regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);
147
148 return stat;
149 }
150
151 /*
152 * Interrupt service routine. This gets called whenever an I2C slave interrupt
153 * occurs.
154 */
i2c_dw_isr_slave(int this_irq,void * dev_id)155 static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
156 {
157 struct dw_i2c_dev *dev = dev_id;
158 unsigned int raw_stat, stat, enabled, tmp;
159 u8 val = 0, slave_activity;
160
161 regmap_read(dev->map, DW_IC_ENABLE, &enabled);
162 regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
163 regmap_read(dev->map, DW_IC_STATUS, &tmp);
164 slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
165
166 if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
167 return IRQ_NONE;
168
169 stat = i2c_dw_read_clear_intrbits_slave(dev);
170 dev_dbg(dev->dev,
171 "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
172 enabled, slave_activity, raw_stat, stat);
173
174 if (stat & DW_IC_INTR_RX_FULL) {
175 if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) {
176 dev->status |= STATUS_WRITE_IN_PROGRESS;
177 dev->status &= ~STATUS_READ_IN_PROGRESS;
178 i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
179 &val);
180 }
181
182 do {
183 regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
184 if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE)
185 i2c_slave_event(dev->slave,
186 I2C_SLAVE_WRITE_REQUESTED,
187 &val);
188 val = tmp;
189 i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
190 &val);
191 regmap_read(dev->map, DW_IC_STATUS, &tmp);
192 } while (tmp & DW_IC_STATUS_RFNE);
193 }
194
195 if (stat & DW_IC_INTR_RD_REQ) {
196 if (slave_activity) {
197 regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
198
199 if (!(dev->status & STATUS_READ_IN_PROGRESS)) {
200 i2c_slave_event(dev->slave,
201 I2C_SLAVE_READ_REQUESTED,
202 &val);
203 dev->status |= STATUS_READ_IN_PROGRESS;
204 dev->status &= ~STATUS_WRITE_IN_PROGRESS;
205 } else {
206 i2c_slave_event(dev->slave,
207 I2C_SLAVE_READ_PROCESSED,
208 &val);
209 }
210 regmap_write(dev->map, DW_IC_DATA_CMD, val);
211 }
212 }
213
214 if (stat & DW_IC_INTR_STOP_DET)
215 i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
216
217 return IRQ_HANDLED;
218 }
219
220 static const struct i2c_algorithm i2c_dw_algo = {
221 .functionality = i2c_dw_func,
222 .reg_slave = i2c_dw_reg_slave,
223 .unreg_slave = i2c_dw_unreg_slave,
224 };
225
i2c_dw_configure_slave(struct dw_i2c_dev * dev)226 void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
227 {
228 dev->functionality = I2C_FUNC_SLAVE;
229
230 dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL |
231 DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED;
232
233 dev->mode = DW_IC_SLAVE;
234 }
235 EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);
236
i2c_dw_probe_slave(struct dw_i2c_dev * dev)237 int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
238 {
239 struct i2c_adapter *adap = &dev->adapter;
240 int ret;
241
242 dev->init = i2c_dw_init_slave;
243
244 ret = i2c_dw_init_regmap(dev);
245 if (ret)
246 return ret;
247
248 ret = i2c_dw_set_sda_hold(dev);
249 if (ret)
250 return ret;
251
252 ret = i2c_dw_set_fifo_size(dev);
253 if (ret)
254 return ret;
255
256 ret = dev->init(dev);
257 if (ret)
258 return ret;
259
260 snprintf(adap->name, sizeof(adap->name),
261 "Synopsys DesignWare I2C Slave adapter");
262 adap->retries = 3;
263 adap->algo = &i2c_dw_algo;
264 adap->dev.parent = dev->dev;
265 i2c_set_adapdata(adap, dev);
266
267 ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
268 IRQF_SHARED, dev_name(dev->dev), dev);
269 if (ret) {
270 dev_err(dev->dev, "failure requesting IRQ %i: %d\n",
271 dev->irq, ret);
272 return ret;
273 }
274
275 ret = i2c_add_numbered_adapter(adap);
276 if (ret)
277 dev_err(dev->dev, "failure adding adapter: %d\n", ret);
278
279 return ret;
280 }
281 EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);
282
283 MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
284 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
285 MODULE_LICENSE("GPL v2");
286 MODULE_IMPORT_NS("I2C_DW_COMMON");
287