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->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");