drivers/i2c/busses/i2c-designware-slave.c

   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->status = 0;
  82
  83         return 0;
  84 }
  85
  86 static int i2c_dw_unreg_slave(struct i2c_client *slave)
  87 {
  88         struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
  89
  90         regmap_write(dev->map, DW_IC_INTR_MASK, 0);
  91         dev->disable(dev);
  92         synchronize_irq(dev->irq);
  93         dev->slave = NULL;
  94         pm_runtime_put(dev->dev);
  95
  96         return 0;
  97 }
  98
  99 static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 100 {
 101         unsigned int stat, dummy;
 102
 103         /*
 104          * The IC_INTR_STAT register just indicates "enabled" interrupts.
 105          * The unmasked raw version of interrupt status bits is available
 106          * in the IC_RAW_INTR_STAT register.
 107          *
 108          * That is,
 109          *   stat = readl(IC_INTR_STAT);
 110          * equals to,
 111          *   stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
 112          *
 113          * The raw version might be useful for debugging purposes.
 114          */
 115         regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
 116
 117         /*
 118          * Do not use the IC_CLR_INTR register to clear interrupts, or
 119          * you'll miss some interrupts, triggered during the period from
 120          * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
 121          *
 122          * Instead, use the separately-prepared IC_CLR_* registers.
 123          */
 124         if (stat & DW_IC_INTR_TX_ABRT)
 125                 regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
 126         if (stat & DW_IC_INTR_RX_UNDER)
 127                 regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
 128         if (stat & DW_IC_INTR_RX_OVER)
 129                 regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
 130         if (stat & DW_IC_INTR_TX_OVER)
 131                 regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
 132         if (stat & DW_IC_INTR_RX_DONE)
 133                 regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
 134         if (stat & DW_IC_INTR_ACTIVITY)
 135                 regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
 136         if (stat & DW_IC_INTR_STOP_DET)
 137                 regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
 138         if (stat & DW_IC_INTR_START_DET)
 139                 regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
 140         if (stat & DW_IC_INTR_GEN_CALL)
 141                 regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);
 142
 143         return stat;
 144 }
 145
 146 /*
 147  * Interrupt service routine. This gets called whenever an I2C slave interrupt
 148  * occurs.
 149  */
 150 static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
 151 {
 152         struct dw_i2c_dev *dev = dev_id;
 153         unsigned int raw_stat, stat, enabled, tmp;
 154         u8 val = 0, slave_activity;
 155
 156         regmap_read(dev->map, DW_IC_ENABLE, &enabled);
 157         regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
 158         regmap_read(dev->map, DW_IC_STATUS, &tmp);
 159         slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
 160
 161         if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
 162                 return IRQ_NONE;
 163
 164         stat = i2c_dw_read_clear_intrbits_slave(dev);
 165         dev_dbg(dev->dev,
 166                 "%#x STATUS SLAVE_ACTIVITY=%#x : RAW_INTR_STAT=%#x : INTR_STAT=%#x\n",
 167                 enabled, slave_activity, raw_stat, stat);
 168
 169         if (stat & DW_IC_INTR_RX_FULL) {
 170                 if (!(dev->status & STATUS_WRITE_IN_PROGRESS)) {
 171                         dev->status |= STATUS_WRITE_IN_PROGRESS;
 172                         dev->status &= ~STATUS_READ_IN_PROGRESS;
 173                         i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_REQUESTED,
 174                                         &val);
 175                 }
 176
 177                 do {
 178                         regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
 179                         if (tmp & DW_IC_DATA_CMD_FIRST_DATA_BYTE)
 180                                 i2c_slave_event(dev->slave,
 181                                                 I2C_SLAVE_WRITE_REQUESTED,
 182                                                 &val);
 183                         val = tmp;
 184                         i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
 185                                         &val);
 186                         regmap_read(dev->map, DW_IC_STATUS, &tmp);
 187                 } while (tmp & DW_IC_STATUS_RFNE);
 188         }
 189
 190         if (stat & DW_IC_INTR_RD_REQ) {
 191                 if (slave_activity) {
 192                         regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
 193
 194                         if (!(dev->status & STATUS_READ_IN_PROGRESS)) {
 195                                 i2c_slave_event(dev->slave,
 196                                                 I2C_SLAVE_READ_REQUESTED,
 197                                                 &val);
 198                                 dev->status |= STATUS_READ_IN_PROGRESS;
 199                                 dev->status &= ~STATUS_WRITE_IN_PROGRESS;
 200                         } else {
 201                                 i2c_slave_event(dev->slave,
 202                                                 I2C_SLAVE_READ_PROCESSED,
 203                                                 &val);
 204                         }
 205                         regmap_write(dev->map, DW_IC_DATA_CMD, val);
 206                 }
 207         }
 208
 209         if (stat & DW_IC_INTR_STOP_DET)
 210                 i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
 211
 212         return IRQ_HANDLED;
 213 }
 214
 215 static const struct i2c_algorithm i2c_dw_algo = {
 216         .functionality = i2c_dw_func,
 217         .reg_slave = i2c_dw_reg_slave,
 218         .unreg_slave = i2c_dw_unreg_slave,
 219 };
 220
 221 void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
 222 {
 223         dev->functionality = I2C_FUNC_SLAVE | DW_IC_DEFAULT_FUNCTIONALITY;
 224
 225         dev->slave_cfg = DW_IC_CON_RX_FIFO_FULL_HLD_CTRL |
 226                          DW_IC_CON_RESTART_EN | DW_IC_CON_STOP_DET_IFADDRESSED;
 227
 228         dev->mode = DW_IC_SLAVE;
 229 }
 230 EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);
 231
 232 int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 233 {
 234         struct i2c_adapter *adap = &dev->adapter;
 235         int ret;
 236
 237         dev->init = i2c_dw_init_slave;
 238         dev->disable = i2c_dw_disable;
 239
 240         ret = i2c_dw_init_regmap(dev);
 241         if (ret)
 242                 return ret;
 243
 244         ret = i2c_dw_set_sda_hold(dev);
 245         if (ret)
 246                 return ret;
 247
 248         ret = i2c_dw_set_fifo_size(dev);
 249         if (ret)
 250                 return ret;
 251
 252         ret = dev->init(dev);
 253         if (ret)
 254                 return ret;
 255
 256         snprintf(adap->name, sizeof(adap->name),
 257                  "Synopsys DesignWare I2C Slave adapter");
 258         adap->retries = 3;
 259         adap->algo = &i2c_dw_algo;
 260         adap->dev.parent = dev->dev;
 261         i2c_set_adapdata(adap, dev);
 262
 263         ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
 264                                IRQF_SHARED, dev_name(dev->dev), dev);
 265         if (ret) {
 266                 dev_err(dev->dev, "failure requesting irq %i: %d\n",
 267                         dev->irq, ret);
 268                 return ret;
 269         }
 270
 271         ret = i2c_add_numbered_adapter(adap);
 272         if (ret)
 273                 dev_err(dev->dev, "failure adding adapter: %d\n", ret);
 274
 275         return ret;
 276 }
 277 EXPORT_SYMBOL_GPL(i2c_dw_probe_slave);
 278
 279 MODULE_AUTHOR("Luis Oliveira <lolivei@synopsys.com>");
 280 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus slave adapter");
 281 MODULE_LICENSE("GPL v2");