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