drivers/i2c/ast_i2c.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Copyright (C) 2012-2020  ASPEED Technology Inc.
   4  * Copyright 2016 IBM Corporation
   5  * Copyright 2017 Google, Inc.
   6  */
   7
   8 #include <common.h>
   9 #include <clk.h>
  10 #include <dm.h>
  11 #include <errno.h>
  12 #include <fdtdec.h>
  13 #include <i2c.h>
  14 #include <log.h>
  15 #include <asm/io.h>
  16 #include <asm/arch/scu_ast2500.h>
  17 #include <linux/err.h>
  18
  19 #include "ast_i2c.h"
  20
  21 #define I2C_TIMEOUT_US 100000
  22 #define I2C_SLEEP_STEP_US 20
  23
  24 #define HIGHSPEED_TTIMEOUT              3
  25
  26 /*
  27  * Device private data
  28  */
  29 struct ast_i2c_priv {
  30         /* This device's clock */
  31         struct clk clk;
  32         /* Device registers */
  33         struct ast_i2c_regs *regs;
  34         /* I2C speed in Hz */
  35         int speed;
  36 };
  37
  38 /*
  39  * Given desired divider ratio, return the value that needs to be set
  40  * in Clock and AC Timing Control register
  41  */
  42 static u32 get_clk_reg_val(ulong divider_ratio)
  43 {
  44         ulong inc = 0, div;
  45         ulong scl_low, scl_high, data;
  46
  47         for (div = 0; divider_ratio >= 16; div++) {
  48                 inc |= (divider_ratio & 1);
  49                 divider_ratio >>= 1;
  50         }
  51         divider_ratio += inc;
  52         scl_low = (divider_ratio >> 1) - 1;
  53         scl_high = divider_ratio - scl_low - 2;
  54         data = I2CD_CACTC_BASE
  55                         | (scl_high << I2CD_TCKHIGH_SHIFT)
  56                         | (scl_low << I2CD_TCKLOW_SHIFT)
  57                         | (div << I2CD_BASE_DIV_SHIFT);
  58
  59         return data;
  60 }
  61
  62 static void ast_i2c_clear_interrupts(struct udevice *dev)
  63 {
  64         struct ast_i2c_priv *priv = dev_get_priv(dev);
  65
  66         writel(~0, &priv->regs->isr);
  67 }
  68
  69 static void ast_i2c_init_bus(struct udevice *dev)
  70 {
  71         struct ast_i2c_priv *priv = dev_get_priv(dev);
  72
  73         /* Reset device */
  74         writel(0, &priv->regs->fcr);
  75         /* Enable Master Mode. Assuming single-master */
  76         writel(I2CD_MASTER_EN
  77                | I2CD_M_SDA_LOCK_EN
  78                | I2CD_MULTI_MASTER_DIS | I2CD_M_SCL_DRIVE_EN,
  79                &priv->regs->fcr);
  80         /* Enable Interrupts */
  81         writel(I2CD_INTR_TX_ACK
  82                | I2CD_INTR_TX_NAK
  83                | I2CD_INTR_RX_DONE
  84                | I2CD_INTR_BUS_RECOVER_DONE
  85                | I2CD_INTR_NORMAL_STOP
  86                | I2CD_INTR_ABNORMAL, &priv->regs->icr);
  87 }
  88
  89 static int ast_i2c_ofdata_to_platdata(struct udevice *dev)
  90 {
  91         struct ast_i2c_priv *priv = dev_get_priv(dev);
  92         int ret;
  93
  94         priv->regs = devfdt_get_addr_ptr(dev);
  95         if (IS_ERR(priv->regs))
  96                 return PTR_ERR(priv->regs);
  97
  98         ret = clk_get_by_index(dev, 0, &priv->clk);
  99         if (ret < 0) {
 100                 debug("%s: Can't get clock for %s: %d\n", __func__, dev->name,
 101                       ret);
 102                 return ret;
 103         }
 104
 105         return 0;
 106 }
 107
 108 static int ast_i2c_probe(struct udevice *dev)
 109 {
 110         struct ast2500_scu *scu;
 111
 112         debug("Enabling I2C%u\n", dev->seq);
 113
 114         /*
 115          * Get all I2C devices out of Reset.
 116          * Only needs to be done once, but doing it for every
 117          * device does not hurt.
 118          */
 119         scu = ast_get_scu();
 120         ast_scu_unlock(scu);
 121         clrbits_le32(&scu->sysreset_ctrl1, SCU_SYSRESET_I2C);
 122         ast_scu_lock(scu);
 123
 124         ast_i2c_init_bus(dev);
 125
 126         return 0;
 127 }
 128
 129 static int ast_i2c_wait_isr(struct udevice *dev, u32 flag)
 130 {
 131         struct ast_i2c_priv *priv = dev_get_priv(dev);
 132         int timeout = I2C_TIMEOUT_US;
 133
 134         while (!(readl(&priv->regs->isr) & flag) && timeout > 0) {
 135                 udelay(I2C_SLEEP_STEP_US);
 136                 timeout -= I2C_SLEEP_STEP_US;
 137         }
 138
 139         ast_i2c_clear_interrupts(dev);
 140         if (timeout <= 0)
 141                 return -ETIMEDOUT;
 142
 143         return 0;
 144 }
 145
 146 static int ast_i2c_send_stop(struct udevice *dev)
 147 {
 148         struct ast_i2c_priv *priv = dev_get_priv(dev);
 149
 150         writel(I2CD_M_STOP_CMD, &priv->regs->csr);
 151
 152         return ast_i2c_wait_isr(dev, I2CD_INTR_NORMAL_STOP);
 153 }
 154
 155 static int ast_i2c_wait_tx(struct udevice *dev)
 156 {
 157         struct ast_i2c_priv *priv = dev_get_priv(dev);
 158         int timeout = I2C_TIMEOUT_US;
 159         u32 flag = I2CD_INTR_TX_ACK | I2CD_INTR_TX_NAK;
 160         u32 status = readl(&priv->regs->isr) & flag;
 161         int ret = 0;
 162
 163         while (!status && timeout > 0) {
 164                 status = readl(&priv->regs->isr) & flag;
 165                 udelay(I2C_SLEEP_STEP_US);
 166                 timeout -= I2C_SLEEP_STEP_US;
 167         }
 168
 169         if (status == I2CD_INTR_TX_NAK)
 170                 ret = -EREMOTEIO;
 171
 172         if (timeout <= 0)
 173                 ret = -ETIMEDOUT;
 174
 175         ast_i2c_clear_interrupts(dev);
 176
 177         return ret;
 178 }
 179
 180 static int ast_i2c_start_txn(struct udevice *dev, uint devaddr)
 181 {
 182         struct ast_i2c_priv *priv = dev_get_priv(dev);
 183
 184         /* Start and Send Device Address */
 185         writel(devaddr, &priv->regs->trbbr);
 186         writel(I2CD_M_START_CMD | I2CD_M_TX_CMD, &priv->regs->csr);
 187
 188         return ast_i2c_wait_tx(dev);
 189 }
 190
 191 static int ast_i2c_read_data(struct udevice *dev, u8 chip_addr, u8 *buffer,
 192                              size_t len, bool send_stop)
 193 {
 194         struct ast_i2c_priv *priv = dev_get_priv(dev);
 195         u32 i2c_cmd = I2CD_M_RX_CMD;
 196         int ret;
 197
 198         ret = ast_i2c_start_txn(dev, (chip_addr << 1) | I2C_M_RD);
 199         if (ret < 0)
 200                 return ret;
 201
 202         for (; len > 0; len--, buffer++) {
 203                 if (len == 1)
 204                         i2c_cmd |= I2CD_M_S_RX_CMD_LAST;
 205                 writel(i2c_cmd, &priv->regs->csr);
 206                 ret = ast_i2c_wait_isr(dev, I2CD_INTR_RX_DONE);
 207                 if (ret < 0)
 208                         return ret;
 209                 *buffer = (readl(&priv->regs->trbbr) & I2CD_RX_DATA_MASK)
 210                                 >> I2CD_RX_DATA_SHIFT;
 211         }
 212         ast_i2c_clear_interrupts(dev);
 213
 214         if (send_stop)
 215                 return ast_i2c_send_stop(dev);
 216
 217         return 0;
 218 }
 219
 220 static int ast_i2c_write_data(struct udevice *dev, u8 chip_addr, u8
 221                               *buffer, size_t len, bool send_stop)
 222 {
 223         struct ast_i2c_priv *priv = dev_get_priv(dev);
 224         int ret;
 225
 226         ret = ast_i2c_start_txn(dev, (chip_addr << 1));
 227         if (ret < 0)
 228                 return ret;
 229
 230         for (; len > 0; len--, buffer++) {
 231                 writel(*buffer, &priv->regs->trbbr);
 232                 writel(I2CD_M_TX_CMD, &priv->regs->csr);
 233                 ret = ast_i2c_wait_tx(dev);
 234                 if (ret < 0)
 235                         return ret;
 236         }
 237
 238         if (send_stop)
 239                 return ast_i2c_send_stop(dev);
 240
 241         return 0;
 242 }
 243
 244 static int ast_i2c_deblock(struct udevice *dev)
 245 {
 246         struct ast_i2c_priv *priv = dev_get_priv(dev);
 247         struct ast_i2c_regs *regs = priv->regs;
 248         u32 csr = readl(&regs->csr);
 249         bool sda_high = csr & I2CD_SDA_LINE_STS;
 250         bool scl_high = csr & I2CD_SCL_LINE_STS;
 251         int ret = 0;
 252
 253         if (sda_high && scl_high) {
 254                 /* Bus is idle, no deblocking needed. */
 255                 return 0;
 256         } else if (sda_high) {
 257                 /* Send stop command */
 258                 debug("Unterminated TXN in (%x), sending stop\n", csr);
 259                 ret = ast_i2c_send_stop(dev);
 260         } else if (scl_high) {
 261                 /* Possibly stuck slave */
 262                 debug("Bus stuck (%x), attempting recovery\n", csr);
 263                 writel(I2CD_BUS_RECOVER_CMD, &regs->csr);
 264                 ret = ast_i2c_wait_isr(dev, I2CD_INTR_BUS_RECOVER_DONE);
 265         } else {
 266                 /* Just try to reinit the device. */
 267                 ast_i2c_init_bus(dev);
 268         }
 269
 270         return ret;
 271 }
 272
 273 static int ast_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
 274 {
 275         int ret;
 276
 277         ret = ast_i2c_deblock(dev);
 278         if (ret < 0)
 279                 return ret;
 280
 281         debug("i2c_xfer: %d messages\n", nmsgs);
 282         for (; nmsgs > 0; nmsgs--, msg++) {
 283                 if (msg->flags & I2C_M_RD) {
 284                         debug("i2c_read: chip=0x%x, len=0x%x, flags=0x%x\n",
 285                               msg->addr, msg->len, msg->flags);
 286                         ret = ast_i2c_read_data(dev, msg->addr, msg->buf,
 287                                                 msg->len, (nmsgs == 1));
 288                 } else {
 289                         debug("i2c_write: chip=0x%x, len=0x%x, flags=0x%x\n",
 290                               msg->addr, msg->len, msg->flags);
 291                         ret = ast_i2c_write_data(dev, msg->addr, msg->buf,
 292                                                  msg->len, (nmsgs == 1));
 293                 }
 294                 if (ret) {
 295                         debug("%s: error (%d)\n", __func__, ret);
 296                         return -EREMOTEIO;
 297                 }
 298         }
 299
 300         return 0;
 301 }
 302
 303 static int ast_i2c_set_speed(struct udevice *dev, unsigned int speed)
 304 {
 305         struct ast_i2c_priv *priv = dev_get_priv(dev);
 306         struct ast_i2c_regs *regs = priv->regs;
 307         ulong i2c_rate, divider;
 308
 309         debug("Setting speed for I2C%d to <%u>\n", dev->seq, speed);
 310         if (!speed) {
 311                 debug("No valid speed specified\n");
 312                 return -EINVAL;
 313         }
 314
 315         i2c_rate = clk_get_rate(&priv->clk);
 316         divider = i2c_rate / speed;
 317
 318         priv->speed = speed;
 319         if (speed > I2C_SPEED_FAST_RATE) {
 320                 debug("Enable High Speed\n");
 321                 setbits_le32(&regs->fcr, I2CD_M_HIGH_SPEED_EN
 322                              | I2CD_M_SDA_DRIVE_1T_EN
 323                              | I2CD_SDA_DRIVE_1T_EN);
 324                 writel(HIGHSPEED_TTIMEOUT, &regs->cactcr2);
 325         } else {
 326                 debug("Enabling Normal Speed\n");
 327                 writel(I2CD_NO_TIMEOUT_CTRL, &regs->cactcr2);
 328         }
 329
 330         writel(get_clk_reg_val(divider), &regs->cactcr1);
 331         ast_i2c_clear_interrupts(dev);
 332
 333         return 0;
 334 }
 335
 336 static const struct dm_i2c_ops ast_i2c_ops = {
 337         .xfer = ast_i2c_xfer,
 338         .set_bus_speed = ast_i2c_set_speed,
 339         .deblock = ast_i2c_deblock,
 340 };
 341
 342 static const struct udevice_id ast_i2c_ids[] = {
 343         { .compatible = "aspeed,ast2400-i2c-bus" },
 344         { .compatible = "aspeed,ast2500-i2c-bus" },
 345         { },
 346 };
 347
 348 U_BOOT_DRIVER(ast_i2c) = {
 349         .name = "ast_i2c",
 350         .id = UCLASS_I2C,
 351         .of_match = ast_i2c_ids,
 352         .probe = ast_i2c_probe,
 353         .ofdata_to_platdata = ast_i2c_ofdata_to_platdata,
 354         .priv_auto_alloc_size = sizeof(struct ast_i2c_priv),
 355         .ops = &ast_i2c_ops,
 356 };