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 #include <linux/delay.h> 10 #include <linux/err.h> 11 #include <linux/errno.h> 12 #include <linux/i2c.h> 13 #include <linux/interrupt.h> 14 #include <linux/io.h> 15 #include <linux/module.h> 16 #include <linux/pm_runtime.h> 17 #include <linux/regmap.h> 18 19 #include "i2c-designware-core.h" 20 21 static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev) 22 { 23 /* Configure Tx/Rx FIFO threshold levels. */ 24 regmap_write(dev->map, DW_IC_TX_TL, 0); 25 regmap_write(dev->map, DW_IC_RX_TL, 0); 26 27 /* Configure the I2C slave. */ 28 regmap_write(dev->map, DW_IC_CON, dev->slave_cfg); 29 regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK); 30 } 31 32 /** 33 * i2c_dw_init_slave() - Initialize the designware i2c slave hardware 34 * @dev: device private data 35 * 36 * This function configures and enables the I2C in slave mode. 37 * This function is called during I2C init function, and in case of timeout at 38 * run time. 39 */ 40 static int i2c_dw_init_slave(struct dw_i2c_dev *dev) 41 { 42 int ret; 43 44 ret = i2c_dw_acquire_lock(dev); 45 if (ret) 46 return ret; 47 48 /* Disable the adapter. */ 49 __i2c_dw_disable(dev); 50 51 /* Write SDA hold time if supported */ 52 if (dev->sda_hold_time) 53 regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time); 54 55 i2c_dw_configure_fifo_slave(dev); 56 i2c_dw_release_lock(dev); 57 58 return 0; 59 } 60 61 static int i2c_dw_reg_slave(struct i2c_client *slave) 62 { 63 struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter); 64 65 if (dev->slave) 66 return -EBUSY; 67 if (slave->flags & I2C_CLIENT_TEN) 68 return -EAFNOSUPPORT; 69 pm_runtime_get_sync(dev->dev); 70 71 /* 72 * Set slave address in the IC_SAR register, 73 * the address to which the DW_apb_i2c responds. 74 */ 75 __i2c_dw_disable_nowait(dev); 76 regmap_write(dev->map, DW_IC_SAR, slave->addr); 77 dev->slave = slave; 78 79 __i2c_dw_enable(dev); 80 81 dev->cmd_err = 0; 82 dev->msg_write_idx = 0; 83 dev->msg_read_idx = 0; 84 dev->msg_err = 0; 85 dev->status = STATUS_IDLE; 86 dev->abort_source = 0; 87 dev->rx_outstanding = 0; 88 89 return 0; 90 } 91 92 static int i2c_dw_unreg_slave(struct i2c_client *slave) 93 { 94 struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter); 95 96 dev->disable_int(dev); 97 dev->disable(dev); 98 synchronize_irq(dev->irq); 99 dev->slave = NULL; 100 pm_runtime_put(dev->dev); 101 102 return 0; 103 } 104 105 static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev) 106 { 107 u32 stat, dummy; 108 109 /* 110 * The IC_INTR_STAT register just indicates "enabled" interrupts. 111 * The unmasked raw version of interrupt status bits is available 112 * in the IC_RAW_INTR_STAT register. 113 * 114 * That is, 115 * stat = readl(IC_INTR_STAT); 116 * equals to, 117 * stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK); 118 * 119 * The raw version might be useful for debugging purposes. 120 */ 121 regmap_read(dev->map, DW_IC_INTR_STAT, &stat); 122 123 /* 124 * Do not use the IC_CLR_INTR register to clear interrupts, or 125 * you'll miss some interrupts, triggered during the period from 126 * readl(IC_INTR_STAT) to readl(IC_CLR_INTR). 127 * 128 * Instead, use the separately-prepared IC_CLR_* registers. 129 */ 130 if (stat & DW_IC_INTR_TX_ABRT) 131 regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy); 132 if (stat & DW_IC_INTR_RX_UNDER) 133 regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy); 134 if (stat & DW_IC_INTR_RX_OVER) 135 regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy); 136 if (stat & DW_IC_INTR_TX_OVER) 137 regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy); 138 if (stat & DW_IC_INTR_RX_DONE) 139 regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy); 140 if (stat & DW_IC_INTR_ACTIVITY) 141 regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy); 142 if (stat & DW_IC_INTR_STOP_DET) 143 regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy); 144 if (stat & DW_IC_INTR_START_DET) 145 regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy); 146 if (stat & DW_IC_INTR_GEN_CALL) 147 regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy); 148 149 return stat; 150 } 151 152 /* 153 * Interrupt service routine. This gets called whenever an I2C slave interrupt 154 * occurs. 155 */ 156 157 static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev) 158 { 159 u32 raw_stat, stat, enabled, tmp; 160 u8 val = 0, slave_activity; 161 162 regmap_read(dev->map, DW_IC_ENABLE, &enabled); 163 regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat); 164 regmap_read(dev->map, DW_IC_STATUS, &tmp); 165 slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6); 166 167 if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave) 168 return 0; 169 170 stat = i2c_dw_read_clear_intrbits_slave(dev); 171 dev_dbg(dev->dev, 172 "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n", 173 enabled, slave_activity, raw_stat, stat); 174 175 if (stat & DW_IC_INTR_RX_FULL) { 176 if (dev->status != STATUS_WRITE_IN_PROGRESS) { 177 dev->status = STATUS_WRITE_IN_PROGRESS; 178 i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED, 179 &val); 180 } 181 182 regmap_read(dev->map, DW_IC_DATA_CMD, &tmp); 183 val = tmp; 184 if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED, 185 &val)) 186 dev_vdbg(dev->dev, "Byte %X acked!", val); 187 } 188 189 if (stat & DW_IC_INTR_RD_REQ) { 190 if (slave_activity) { 191 regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp); 192 193 dev->status = STATUS_READ_IN_PROGRESS; 194 if (!i2c_slave_event(dev->slave, 195 I2C_SLAVE_READ_REQUESTED, 196 &val)) 197 regmap_write(dev->map, DW_IC_DATA_CMD, val); 198 } 199 } 200 201 if (stat & DW_IC_INTR_RX_DONE) { 202 if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED, 203 &val)) 204 regmap_read(dev->map, DW_IC_CLR_RX_DONE, &tmp); 205 } 206 207 if (stat & DW_IC_INTR_STOP_DET) { 208 dev->status = STATUS_IDLE; 209 i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val); 210 } 211 212 return 1; 213 } 214 215 static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id) 216 { 217 struct dw_i2c_dev *dev = dev_id; 218 int ret; 219 220 ret = i2c_dw_irq_handler_slave(dev); 221 if (ret > 0) 222 complete(&dev->cmd_complete); 223 224 return IRQ_RETVAL(ret); 225 } 226 227 static const struct i2c_algorithm i2c_dw_algo = { 228 .functionality = i2c_dw_func, 229 .reg_slave = i2c_dw_reg_slave, 230 .unreg_slave = i2c_dw_unreg_slave, 231 }; 232 233 void i2c_dw_configure_slave(struct dw_i2c_dev *dev) 234 { 235 dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY; 236 237 dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL | 238 DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED; 239 240 dev->mode = DW_IC_SLAVE; 241 } 242 EXPORT_SYMBOL_GPL(i2c_dw_configure_slave); 243 244 int i2c_dw_probe_slave(struct dw_i2c_dev *dev) 245 { 246 struct i2c_adapter *adap = &dev->adapter; 247 int ret; 248 249 init_completion(&dev->cmd_complete); 250 251 dev->init = i2c_dw_init_slave; 252 dev->disable = i2c_dw_disable; 253 dev->disable_int = i2c_dw_disable_int; 254 255 ret = i2c_dw_init_regmap(dev); 256 if (ret) 257 return ret; 258 259 ret = i2c_dw_set_sda_hold(dev); 260 if (ret) 261 return ret; 262 263 ret = i2c_dw_set_fifo_size(dev); 264 if (ret) 265 return ret; 266 267 ret = dev->init(dev); 268 if (ret) 269 return ret; 270 271 snprintf(adap->name, sizeof(adap->name), 272 "Synopsys DesignWare I2C Slave adapter"); 273 adap->retries = 3; 274 adap->algo = &i2c_dw_algo; 275 adap->dev.parent = dev->dev; 276 i2c_set_adapdata(adap, dev); 277 278 ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave, 279 IRQF_SHARED, dev_name(dev->dev), dev); 280 if (ret) { 281 dev_err(dev->dev, "failure requesting irq %i: %d\n", 282 dev->irq, ret); 283 return ret; 284 } 285 286 ret = i2c_add_numbered_adapter(adap); 287 if (ret) 288 dev_err(dev->dev, "failure adding adapter: %d\n", ret); 289 290 return ret; 291 } 292 EXPORT_SYMBOL_GPL(i2c_dw_probe_slave); 293 294 MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>"); 295 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter"); 296 MODULE_LICENSE("GPL v2"); 297