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/delay.h>
  18 #include <linux/err.h>
  19 #include <reset.h>
  20
  21 #include "ast_i2c.h"
  22
  23 #define I2C_TIMEOUT_US 100000
  24 #define I2C_SLEEP_STEP_US 20
  25
  26 #define HIGHSPEED_TTIMEOUT              3
  27
  28 /*
  29  * Device private data
  30  */
  31 struct ast_i2c_priv {
  32         /* This device's clock */
  33         struct clk clk;
  34         /* Device registers */
  35         struct ast_i2c_regs *regs;
  36         /* I2C speed in Hz */
  37         int speed;
  38 };
  39
  40 /*
  41  * Given desired divider ratio, return the value that needs to be set
  42  * in Clock and AC Timing Control register
  43  */
  44 static u32 get_clk_reg_val(ulong divider_ratio)
  45 {
  46         ulong inc = 0, div;
  47         ulong scl_low, scl_high, data;
  48
  49         for (div = 0; divider_ratio >= 16; div++) {
  50                 inc |= (divider_ratio & 1);
  51                 divider_ratio >>= 1;
  52         }
  53         divider_ratio += inc;
  54         scl_low = (divider_ratio >> 1) - 1;
  55         scl_high = divider_ratio - scl_low - 2;
  56         data = I2CD_CACTC_BASE
  57                         | (scl_high << I2CD_TCKHIGH_SHIFT)
  58                         | (scl_low << I2CD_TCKLOW_SHIFT)
  59                         | (div << I2CD_BASE_DIV_SHIFT);
  60
  61         return data;
  62 }
  63
  64 static void ast_i2c_clear_interrupts(struct udevice *dev)
  65 {
  66         struct ast_i2c_priv *priv = dev_get_priv(dev);
  67
  68         writel(~0, &priv->regs->isr);
  69 }
  70
  71 static void ast_i2c_init_bus(struct udevice *dev)
  72 {
  73         struct ast_i2c_priv *priv = dev_get_priv(dev);
  74
  75         /* Reset device */
  76         writel(0, &priv->regs->fcr);
  77         /* Enable Master Mode. Assuming single-master */
  78         writel(I2CD_MASTER_EN
  79                | I2CD_M_SDA_LOCK_EN
  80                | I2CD_MULTI_MASTER_DIS,
  81                &priv->regs->fcr);
  82         /* Enable Interrupts */
  83         writel(I2CD_INTR_TX_ACK
  84                | I2CD_INTR_TX_NAK
  85                | I2CD_INTR_RX_DONE
  86                | I2CD_INTR_BUS_RECOVER_DONE
  87                | I2CD_INTR_NORMAL_STOP
  88                | I2CD_INTR_ABNORMAL, &priv->regs->icr);
  89 }
  90
  91 static int ast_i2c_of_to_plat(struct udevice *dev)
  92 {
  93         struct ast_i2c_priv *priv = dev_get_priv(dev);
  94         int ret;
  95
  96         priv->regs = dev_read_addr_ptr(dev);
  97         if (!priv->regs)
  98                 return -EINVAL;
  99
 100         ret = clk_get_by_index(dev, 0, &priv->clk);
 101         if (ret < 0) {
 102                 debug("%s: Can't get clock for %s: %d\n", __func__, dev->name,
 103                       ret);
 104                 return ret;
 105         }
 106
 107         return 0;
 108 }
 109
 110 static int ast_i2c_probe(struct udevice *dev)
 111 {
 112         struct reset_ctl reset_ctl;
 113         int rc;
 114
 115         debug("Enabling I2C%u\n", dev_seq(dev));
 116
 117         /*
 118          * Get all I2C devices out of Reset.
 119          *
 120          * Only needs to be done once so test before performing reset.
 121          */
 122         rc = reset_get_by_index(dev, 0, &reset_ctl);
 123         if (rc) {
 124                 printf("%s: Failed to get reset signal\n", __func__);
 125                 return rc;
 126         }
 127
 128         if (reset_status(&reset_ctl) > 0) {
 129                 reset_assert(&reset_ctl);
 130                 reset_deassert(&reset_ctl);
 131         }
 132
 133         ast_i2c_init_bus(dev);
 134
 135         return 0;
 136 }
 137
 138 static int ast_i2c_wait_isr(struct udevice *dev, u32 flag)
 139 {
 140         struct ast_i2c_priv *priv = dev_get_priv(dev);
 141         int timeout = I2C_TIMEOUT_US;
 142
 143         while (!(readl(&priv->regs->isr) & flag) && timeout > 0) {
 144                 udelay(I2C_SLEEP_STEP_US);
 145                 timeout -= I2C_SLEEP_STEP_US;
 146         }
 147
 148         ast_i2c_clear_interrupts(dev);
 149         if (timeout <= 0)
 150                 return -ETIMEDOUT;
 151
 152         return 0;
 153 }
 154
 155 static int ast_i2c_send_stop(struct udevice *dev)
 156 {
 157         struct ast_i2c_priv *priv = dev_get_priv(dev);
 158
 159         writel(I2CD_M_STOP_CMD, &priv->regs->csr);
 160
 161         return ast_i2c_wait_isr(dev, I2CD_INTR_NORMAL_STOP);
 162 }
 163
 164 static int ast_i2c_wait_tx(struct udevice *dev)
 165 {
 166         struct ast_i2c_priv *priv = dev_get_priv(dev);
 167         int timeout = I2C_TIMEOUT_US;
 168         u32 flag = I2CD_INTR_TX_ACK | I2CD_INTR_TX_NAK;
 169         u32 status = readl(&priv->regs->isr) & flag;
 170         int ret = 0;
 171
 172         while (!status && timeout > 0) {
 173                 status = readl(&priv->regs->isr) & flag;
 174                 udelay(I2C_SLEEP_STEP_US);
 175                 timeout -= I2C_SLEEP_STEP_US;
 176         }
 177
 178         if (status == I2CD_INTR_TX_NAK)
 179                 ret = -EREMOTEIO;
 180
 181         if (timeout <= 0)
 182                 ret = -ETIMEDOUT;
 183
 184         ast_i2c_clear_interrupts(dev);
 185
 186         return ret;
 187 }
 188
 189 static int ast_i2c_start_txn(struct udevice *dev, uint devaddr)
 190 {
 191         struct ast_i2c_priv *priv = dev_get_priv(dev);
 192
 193         /* Start and Send Device Address */
 194         writel(devaddr, &priv->regs->trbbr);
 195         writel(I2CD_M_START_CMD | I2CD_M_TX_CMD, &priv->regs->csr);
 196
 197         return ast_i2c_wait_tx(dev);
 198 }
 199
 200 static int ast_i2c_read_data(struct udevice *dev, u8 chip_addr, u8 *buffer,
 201                              size_t len, bool send_stop)
 202 {
 203         struct ast_i2c_priv *priv = dev_get_priv(dev);
 204         u32 i2c_cmd = I2CD_M_RX_CMD;
 205         int ret;
 206
 207         ret = ast_i2c_start_txn(dev, (chip_addr << 1) | I2C_M_RD);
 208         if (ret < 0)
 209                 return ret;
 210
 211         for (; len > 0; len--, buffer++) {
 212                 if (len == 1)
 213                         i2c_cmd |= I2CD_M_S_RX_CMD_LAST;
 214                 writel(i2c_cmd, &priv->regs->csr);
 215                 ret = ast_i2c_wait_isr(dev, I2CD_INTR_RX_DONE);
 216                 if (ret < 0)
 217                         return ret;
 218                 *buffer = (readl(&priv->regs->trbbr) & I2CD_RX_DATA_MASK)
 219                                 >> I2CD_RX_DATA_SHIFT;
 220         }
 221         ast_i2c_clear_interrupts(dev);
 222
 223         if (send_stop)
 224                 return ast_i2c_send_stop(dev);
 225
 226         return 0;
 227 }
 228
 229 static int ast_i2c_write_data(struct udevice *dev, u8 chip_addr, u8
 230                               *buffer, size_t len, bool send_stop)
 231 {
 232         struct ast_i2c_priv *priv = dev_get_priv(dev);
 233         int ret;
 234
 235         ret = ast_i2c_start_txn(dev, (chip_addr << 1));
 236         if (ret < 0)
 237                 return ret;
 238
 239         for (; len > 0; len--, buffer++) {
 240                 writel(*buffer, &priv->regs->trbbr);
 241                 writel(I2CD_M_TX_CMD, &priv->regs->csr);
 242                 ret = ast_i2c_wait_tx(dev);
 243                 if (ret < 0)
 244                         return ret;
 245         }
 246
 247         if (send_stop)
 248                 return ast_i2c_send_stop(dev);
 249
 250         return 0;
 251 }
 252
 253 static int ast_i2c_deblock(struct udevice *dev)
 254 {
 255         struct ast_i2c_priv *priv = dev_get_priv(dev);
 256         struct ast_i2c_regs *regs = priv->regs;
 257         u32 csr = readl(&regs->csr);
 258         bool sda_high = csr & I2CD_SDA_LINE_STS;
 259         bool scl_high = csr & I2CD_SCL_LINE_STS;
 260         int ret = 0;
 261
 262         if (sda_high && scl_high) {
 263                 /* Bus is idle, no deblocking needed. */
 264                 return 0;
 265         } else if (sda_high) {
 266                 /* Send stop command */
 267                 debug("Unterminated TXN in (%x), sending stop\n", csr);
 268                 ret = ast_i2c_send_stop(dev);
 269         } else if (scl_high) {
 270                 /* Possibly stuck slave */
 271                 debug("Bus stuck (%x), attempting recovery\n", csr);
 272                 writel(I2CD_BUS_RECOVER_CMD, &regs->csr);
 273                 ret = ast_i2c_wait_isr(dev, I2CD_INTR_BUS_RECOVER_DONE);
 274         } else {
 275                 /* Just try to reinit the device. */
 276                 ast_i2c_init_bus(dev);
 277         }
 278
 279         return ret;
 280 }
 281
 282 static int ast_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
 283 {
 284         int ret;
 285
 286         ret = ast_i2c_deblock(dev);
 287         if (ret < 0)
 288                 return ret;
 289
 290         debug("i2c_xfer: %d messages\n", nmsgs);
 291         for (; nmsgs > 0; nmsgs--, msg++) {
 292                 if (msg->flags & I2C_M_RD) {
 293                         debug("i2c_read: chip=0x%x, len=0x%x, flags=0x%x\n",
 294                               msg->addr, msg->len, msg->flags);
 295                         ret = ast_i2c_read_data(dev, msg->addr, msg->buf,
 296                                                 msg->len, (nmsgs == 1));
 297                 } else {
 298                         debug("i2c_write: chip=0x%x, len=0x%x, flags=0x%x\n",
 299                               msg->addr, msg->len, msg->flags);
 300                         ret = ast_i2c_write_data(dev, msg->addr, msg->buf,
 301                                                  msg->len, (nmsgs == 1));
 302                 }
 303                 if (ret) {
 304                         debug("%s: error (%d)\n", __func__, ret);
 305                         return -EREMOTEIO;
 306                 }
 307         }
 308
 309         return 0;
 310 }
 311
 312 static int ast_i2c_set_speed(struct udevice *dev, unsigned int speed)
 313 {
 314         struct ast_i2c_priv *priv = dev_get_priv(dev);
 315         struct ast_i2c_regs *regs = priv->regs;
 316         ulong i2c_rate, divider;
 317
 318         debug("Setting speed for I2C%d to <%u>\n", dev_seq(dev), speed);
 319         if (!speed) {
 320                 debug("No valid speed specified\n");
 321                 return -EINVAL;
 322         }
 323
 324         i2c_rate = clk_get_rate(&priv->clk);
 325         divider = i2c_rate / speed;
 326
 327         priv->speed = speed;
 328         if (speed > I2C_SPEED_FAST_RATE) {
 329                 debug("Enable High Speed\n");
 330                 setbits_le32(&regs->fcr, I2CD_M_HIGH_SPEED_EN
 331                              | I2CD_M_SDA_DRIVE_1T_EN
 332                              | I2CD_SDA_DRIVE_1T_EN);
 333                 writel(HIGHSPEED_TTIMEOUT, &regs->cactcr2);
 334         } else {
 335                 debug("Enabling Normal Speed\n");
 336                 writel(I2CD_NO_TIMEOUT_CTRL, &regs->cactcr2);
 337         }
 338
 339         writel(get_clk_reg_val(divider), &regs->cactcr1);
 340         ast_i2c_clear_interrupts(dev);
 341
 342         return 0;
 343 }
 344
 345 static const struct dm_i2c_ops ast_i2c_ops = {
 346         .xfer = ast_i2c_xfer,
 347         .set_bus_speed = ast_i2c_set_speed,
 348         .deblock = ast_i2c_deblock,
 349 };
 350
 351 static const struct udevice_id ast_i2c_ids[] = {
 352         { .compatible = "aspeed,ast2400-i2c-bus" },
 353         { .compatible = "aspeed,ast2500-i2c-bus" },
 354         { .compatible = "aspeed,ast2600-i2c-bus" },
 355         { },
 356 };
 357
 358 U_BOOT_DRIVER(ast_i2c) = {
 359         .name = "ast_i2c",
 360         .id = UCLASS_I2C,
 361         .of_match = ast_i2c_ids,
 362         .probe = ast_i2c_probe,
 363         .of_to_plat = ast_i2c_of_to_plat,
 364         .priv_auto      = sizeof(struct ast_i2c_priv),
 365         .ops = &ast_i2c_ops,
 366 };