drivers/i2c/rcar_iic.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Renesas RCar IIC driver
   4  *
   5  * Copyright (C) 2017 Marek Vasut <[email protected]>
   6  *
   7  * Based on
   8  * Copyright (C) 2011, 2013 Renesas Solutions Corp.
   9  * Copyright (C) 2011, 2013 Nobuhiro Iwamatsu <[email protected]>
  10  */
  11
  12 #include <clk.h>
  13 #include <dm.h>
  14 #include <i2c.h>
  15 #include <asm/io.h>
  16 #include <linux/bitops.h>
  17 #include <linux/delay.h>
  18
  19 struct rcar_iic_priv {
  20         void __iomem            *base;
  21         struct clk              clk;
  22         u8                      iccl;
  23         u8                      icch;
  24 };
  25
  26 #define RCAR_IIC_ICDR           0x00
  27 #define RCAR_IIC_ICCR           0x04
  28 #define RCAR_IIC_ICSR           0x08
  29 #define RCAR_IIC_ICIC           0x0c
  30 #define RCAR_IIC_ICCL           0x10
  31 #define RCAR_IIC_ICCH           0x14
  32
  33 /* ICCR */
  34 #define RCAR_IIC_ICCR_ICE       BIT(7)
  35 #define RCAR_IIC_ICCR_RACK      BIT(6)
  36 #define RCAR_IIC_ICCR_RTS       BIT(4)
  37 #define RCAR_IIC_ICCR_BUSY      BIT(2)
  38 #define RCAR_IIC_ICCR_SCP       BIT(0)
  39
  40 /* ICSR / ICIC */
  41 #define RCAR_IC_BUSY            BIT(4)
  42 #define RCAR_IC_TACK            BIT(2)
  43 #define RCAR_IC_DTE             BIT(0)
  44
  45 #define IRQ_WAIT 1000
  46
  47 static void sh_irq_dte(struct udevice *dev)
  48 {
  49         struct rcar_iic_priv *priv = dev_get_priv(dev);
  50         int i;
  51
  52         for (i = 0; i < IRQ_WAIT; i++) {
  53                 if (RCAR_IC_DTE & readb(priv->base + RCAR_IIC_ICSR))
  54                         break;
  55                 udelay(10);
  56         }
  57 }
  58
  59 static int sh_irq_dte_with_tack(struct udevice *dev)
  60 {
  61         struct rcar_iic_priv *priv = dev_get_priv(dev);
  62         u8 icsr;
  63         int i;
  64
  65         for (i = 0; i < IRQ_WAIT; i++) {
  66                 icsr = readb(priv->base + RCAR_IIC_ICSR);
  67                 if (RCAR_IC_DTE & icsr)
  68                         break;
  69                 if (RCAR_IC_TACK & icsr)
  70                         return -ETIMEDOUT;
  71                 udelay(10);
  72         }
  73         return 0;
  74 }
  75
  76 static void sh_irq_busy(struct udevice *dev)
  77 {
  78         struct rcar_iic_priv *priv = dev_get_priv(dev);
  79         int i;
  80
  81         for (i = 0; i < IRQ_WAIT; i++) {
  82                 if (!(RCAR_IC_BUSY & readb(priv->base + RCAR_IIC_ICSR)))
  83                         break;
  84                 udelay(10);
  85         }
  86 }
  87
  88 static int rcar_iic_set_addr(struct udevice *dev, u8 chip, u8 read)
  89 {
  90         struct rcar_iic_priv *priv = dev_get_priv(dev);
  91
  92         clrbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
  93         setbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
  94
  95         writeb(priv->iccl, priv->base + RCAR_IIC_ICCL);
  96         writeb(priv->icch, priv->base + RCAR_IIC_ICCH);
  97         writeb(RCAR_IC_TACK, priv->base + RCAR_IIC_ICIC);
  98
  99         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RTS | RCAR_IIC_ICCR_BUSY,
 100                priv->base + RCAR_IIC_ICCR);
 101         sh_irq_dte(dev);
 102
 103         clrbits_8(priv->base + RCAR_IIC_ICSR, RCAR_IC_TACK);
 104         writeb(chip << 1 | read, priv->base + RCAR_IIC_ICDR);
 105         return sh_irq_dte_with_tack(dev);
 106 }
 107
 108 static void rcar_iic_finish(struct udevice *dev)
 109 {
 110         struct rcar_iic_priv *priv = dev_get_priv(dev);
 111
 112         writeb(0, priv->base + RCAR_IIC_ICSR);
 113         clrbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
 114 }
 115
 116 static int rcar_iic_read_common(struct udevice *dev, struct i2c_msg *msg)
 117 {
 118         struct rcar_iic_priv *priv = dev_get_priv(dev);
 119         int i, ret = -EREMOTEIO;
 120
 121         if (rcar_iic_set_addr(dev, msg->addr, 1) != 0)
 122                 goto err;
 123
 124         udelay(10);
 125
 126         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_SCP,
 127                priv->base + RCAR_IIC_ICCR);
 128
 129         for (i = 0; i < msg->len; i++) {
 130                 if (sh_irq_dte_with_tack(dev) != 0)
 131                         goto err;
 132
 133                 msg->buf[i] = readb(priv->base + RCAR_IIC_ICDR) & 0xff;
 134
 135                 if (msg->len - 1 == i) {
 136                         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RACK,
 137                                priv->base + RCAR_IIC_ICCR);
 138                 }
 139         }
 140
 141         sh_irq_busy(dev);
 142         ret = 0;
 143
 144 err:
 145         rcar_iic_finish(dev);
 146         return ret;
 147 }
 148
 149 static int rcar_iic_write_common(struct udevice *dev, struct i2c_msg *msg)
 150 {
 151         struct rcar_iic_priv *priv = dev_get_priv(dev);
 152         int i, ret = -EREMOTEIO;
 153
 154         if (rcar_iic_set_addr(dev, msg->addr, 0) != 0)
 155                 goto err;
 156
 157         udelay(10);
 158
 159         for (i = 0; i < msg->len; i++) {
 160                 writeb(msg->buf[i], priv->base + RCAR_IIC_ICDR);
 161                 if (sh_irq_dte_with_tack(dev) != 0)
 162                         goto err;
 163         }
 164
 165         if (msg->flags & I2C_M_STOP) {
 166                 writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RTS,
 167                        priv->base + RCAR_IIC_ICCR);
 168                 if (sh_irq_dte_with_tack(dev) != 0)
 169                         goto err;
 170         }
 171
 172         sh_irq_busy(dev);
 173         ret = 0;
 174
 175 err:
 176         rcar_iic_finish(dev);
 177         return ret;
 178 }
 179
 180 static int rcar_iic_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
 181 {
 182         int ret;
 183
 184         for (; nmsgs > 0; nmsgs--, msg++) {
 185                 if (msg->flags & I2C_M_RD)
 186                         ret = rcar_iic_read_common(dev, msg);
 187                 else
 188                         ret = rcar_iic_write_common(dev, msg);
 189
 190                 if (ret)
 191                         return -EREMOTEIO;
 192         }
 193
 194         return ret;
 195 }
 196
 197 static int rcar_iic_set_speed(struct udevice *dev, uint speed)
 198 {
 199         struct rcar_iic_priv *priv = dev_get_priv(dev);
 200         const unsigned int ratio_high = 4;
 201         const unsigned int ratio_low = 5;
 202         int clkrate, denom;
 203
 204         clkrate = clk_get_rate(&priv->clk);
 205         if (clkrate < 0)
 206                 return clkrate;
 207
 208         /*
 209          * Calculate the value for ICCL and ICCH. From the data sheet:
 210          * iccl = (p-clock / transfer-rate) * (L / (L + H))
 211          * icch = (p clock / transfer rate) * (H / (L + H))
 212          * where L and H are the SCL low and high ratio.
 213          */
 214         denom = speed * (ratio_high + ratio_low);
 215         priv->iccl = DIV_ROUND_CLOSEST(clkrate * ratio_low, denom);
 216         priv->icch = DIV_ROUND_CLOSEST(clkrate * ratio_high, denom);
 217
 218         return 0;
 219 }
 220
 221 static int rcar_iic_probe_chip(struct udevice *dev, uint addr, uint flags)
 222 {
 223         struct rcar_iic_priv *priv = dev_get_priv(dev);
 224         int ret;
 225
 226         rcar_iic_set_addr(dev, addr, 1);
 227         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_SCP,
 228                priv->base + RCAR_IIC_ICCR);
 229         ret = sh_irq_dte_with_tack(dev);
 230         rcar_iic_finish(dev);
 231
 232         return ret;
 233 }
 234
 235 static int rcar_iic_probe(struct udevice *dev)
 236 {
 237         struct rcar_iic_priv *priv = dev_get_priv(dev);
 238         int ret;
 239
 240         priv->base = dev_read_addr_ptr(dev);
 241
 242         ret = clk_get_by_index(dev, 0, &priv->clk);
 243         if (ret)
 244                 return ret;
 245
 246         ret = clk_enable(&priv->clk);
 247         if (ret)
 248                 return ret;
 249
 250         rcar_iic_finish(dev);
 251
 252         return rcar_iic_set_speed(dev, I2C_SPEED_STANDARD_RATE);
 253 }
 254
 255 static const struct dm_i2c_ops rcar_iic_ops = {
 256         .xfer           = rcar_iic_xfer,
 257         .probe_chip     = rcar_iic_probe_chip,
 258         .set_bus_speed  = rcar_iic_set_speed,
 259 };
 260
 261 static const struct udevice_id rcar_iic_ids[] = {
 262         { .compatible = "renesas,rmobile-iic" },
 263         { }
 264 };
 265
 266 U_BOOT_DRIVER(iic_rcar) = {
 267         .name           = "iic_rcar",
 268         .id             = UCLASS_I2C,
 269         .of_match       = rcar_iic_ids,
 270         .probe          = rcar_iic_probe,
 271         .priv_auto      = sizeof(struct rcar_iic_priv),
 272         .ops            = &rcar_iic_ops,
 273 };