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