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 <marek.vasut@gmail.com>
   6  *
   7  * Based on
   8  * Copyright (C) 2011, 2013 Renesas Solutions Corp.
   9  * Copyright (C) 2011, 2013 Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
  10  */
  11
  12 #include <common.h>
  13 #include <clk.h>
  14 #include <dm.h>
  15 #include <i2c.h>
  16 #include <asm/io.h>
  17 #include <linux/bitops.h>
  18 #include <linux/delay.h>
  19
  20 struct rcar_iic_priv {
  21         void __iomem            *base;
  22         struct clk              clk;
  23         u8                      iccl;
  24         u8                      icch;
  25 };
  26
  27 #define RCAR_IIC_ICDR           0x00
  28 #define RCAR_IIC_ICCR           0x04
  29 #define RCAR_IIC_ICSR           0x08
  30 #define RCAR_IIC_ICIC           0x0c
  31 #define RCAR_IIC_ICCL           0x10
  32 #define RCAR_IIC_ICCH           0x14
  33
  34 /* ICCR */
  35 #define RCAR_IIC_ICCR_ICE       BIT(7)
  36 #define RCAR_IIC_ICCR_RACK      BIT(6)
  37 #define RCAR_IIC_ICCR_RTS       BIT(4)
  38 #define RCAR_IIC_ICCR_BUSY      BIT(2)
  39 #define RCAR_IIC_ICCR_SCP       BIT(0)
  40
  41 /* ICSR / ICIC */
  42 #define RCAR_IC_BUSY            BIT(4)
  43 #define RCAR_IC_TACK            BIT(2)
  44 #define RCAR_IC_DTE             BIT(0)
  45
  46 #define IRQ_WAIT 1000
  47
  48 static void sh_irq_dte(struct udevice *dev)
  49 {
  50         struct rcar_iic_priv *priv = dev_get_priv(dev);
  51         int i;
  52
  53         for (i = 0; i < IRQ_WAIT; i++) {
  54                 if (RCAR_IC_DTE & readb(priv->base + RCAR_IIC_ICSR))
  55                         break;
  56                 udelay(10);
  57         }
  58 }
  59
  60 static int sh_irq_dte_with_tack(struct udevice *dev)
  61 {
  62         struct rcar_iic_priv *priv = dev_get_priv(dev);
  63         u8 icsr;
  64         int i;
  65
  66         for (i = 0; i < IRQ_WAIT; i++) {
  67                 icsr = readb(priv->base + RCAR_IIC_ICSR);
  68                 if (RCAR_IC_DTE & icsr)
  69                         break;
  70                 if (RCAR_IC_TACK & icsr)
  71                         return -ETIMEDOUT;
  72                 udelay(10);
  73         }
  74         return 0;
  75 }
  76
  77 static void sh_irq_busy(struct udevice *dev)
  78 {
  79         struct rcar_iic_priv *priv = dev_get_priv(dev);
  80         int i;
  81
  82         for (i = 0; i < IRQ_WAIT; i++) {
  83                 if (!(RCAR_IC_BUSY & readb(priv->base + RCAR_IIC_ICSR)))
  84                         break;
  85                 udelay(10);
  86         }
  87 }
  88
  89 static int rcar_iic_set_addr(struct udevice *dev, u8 chip, u8 read)
  90 {
  91         struct rcar_iic_priv *priv = dev_get_priv(dev);
  92
  93         clrbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
  94         setbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
  95
  96         writeb(priv->iccl, priv->base + RCAR_IIC_ICCL);
  97         writeb(priv->icch, priv->base + RCAR_IIC_ICCH);
  98         writeb(RCAR_IC_TACK, priv->base + RCAR_IIC_ICIC);
  99
 100         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RTS | RCAR_IIC_ICCR_BUSY,
 101                priv->base + RCAR_IIC_ICCR);
 102         sh_irq_dte(dev);
 103
 104         clrbits_8(priv->base + RCAR_IIC_ICSR, RCAR_IC_TACK);
 105         writeb(chip << 1 | read, priv->base + RCAR_IIC_ICDR);
 106         return sh_irq_dte_with_tack(dev);
 107 }
 108
 109 static void rcar_iic_finish(struct udevice *dev)
 110 {
 111         struct rcar_iic_priv *priv = dev_get_priv(dev);
 112
 113         writeb(0, priv->base + RCAR_IIC_ICSR);
 114         clrbits_8(priv->base + RCAR_IIC_ICCR, RCAR_IIC_ICCR_ICE);
 115 }
 116
 117 static int rcar_iic_read_common(struct udevice *dev, struct i2c_msg *msg)
 118 {
 119         struct rcar_iic_priv *priv = dev_get_priv(dev);
 120         int i, ret = -EREMOTEIO;
 121
 122         if (rcar_iic_set_addr(dev, msg->addr, 1) != 0)
 123                 goto err;
 124
 125         udelay(10);
 126
 127         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_SCP,
 128                priv->base + RCAR_IIC_ICCR);
 129
 130         for (i = 0; i < msg->len; i++) {
 131                 if (sh_irq_dte_with_tack(dev) != 0)
 132                         goto err;
 133
 134                 msg->buf[i] = readb(priv->base + RCAR_IIC_ICDR) & 0xff;
 135
 136                 if (msg->len - 1 == i) {
 137                         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RACK,
 138                                priv->base + RCAR_IIC_ICCR);
 139                 }
 140         }
 141
 142         sh_irq_busy(dev);
 143         ret = 0;
 144
 145 err:
 146         rcar_iic_finish(dev);
 147         return ret;
 148 }
 149
 150 static int rcar_iic_write_common(struct udevice *dev, struct i2c_msg *msg)
 151 {
 152         struct rcar_iic_priv *priv = dev_get_priv(dev);
 153         int i, ret = -EREMOTEIO;
 154
 155         if (rcar_iic_set_addr(dev, msg->addr, 0) != 0)
 156                 goto err;
 157
 158         udelay(10);
 159
 160         for (i = 0; i < msg->len; i++) {
 161                 writeb(msg->buf[i], priv->base + RCAR_IIC_ICDR);
 162                 if (sh_irq_dte_with_tack(dev) != 0)
 163                         goto err;
 164         }
 165
 166         if (msg->flags & I2C_M_STOP) {
 167                 writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_RTS,
 168                        priv->base + RCAR_IIC_ICCR);
 169                 if (sh_irq_dte_with_tack(dev) != 0)
 170                         goto err;
 171         }
 172
 173         sh_irq_busy(dev);
 174         ret = 0;
 175
 176 err:
 177         rcar_iic_finish(dev);
 178         return ret;
 179 }
 180
 181 static int rcar_iic_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
 182 {
 183         int ret;
 184
 185         for (; nmsgs > 0; nmsgs--, msg++) {
 186                 if (msg->flags & I2C_M_RD)
 187                         ret = rcar_iic_read_common(dev, msg);
 188                 else
 189                         ret = rcar_iic_write_common(dev, msg);
 190
 191                 if (ret)
 192                         return -EREMOTEIO;
 193         }
 194
 195         return ret;
 196 }
 197
 198 static int rcar_iic_set_speed(struct udevice *dev, uint speed)
 199 {
 200         struct rcar_iic_priv *priv = dev_get_priv(dev);
 201         const unsigned int ratio_high = 4;
 202         const unsigned int ratio_low = 5;
 203         int clkrate, denom;
 204
 205         clkrate = clk_get_rate(&priv->clk);
 206         if (clkrate < 0)
 207                 return clkrate;
 208
 209         /*
 210          * Calculate the value for ICCL and ICCH. From the data sheet:
 211          * iccl = (p-clock / transfer-rate) * (L / (L + H))
 212          * icch = (p clock / transfer rate) * (H / (L + H))
 213          * where L and H are the SCL low and high ratio.
 214          */
 215         denom = speed * (ratio_high + ratio_low);
 216         priv->iccl = DIV_ROUND_CLOSEST(clkrate * ratio_low, denom);
 217         priv->icch = DIV_ROUND_CLOSEST(clkrate * ratio_high, denom);
 218
 219         return 0;
 220 }
 221
 222 static int rcar_iic_probe_chip(struct udevice *dev, uint addr, uint flags)
 223 {
 224         struct rcar_iic_priv *priv = dev_get_priv(dev);
 225         int ret;
 226
 227         rcar_iic_set_addr(dev, addr, 1);
 228         writeb(RCAR_IIC_ICCR_ICE | RCAR_IIC_ICCR_SCP,
 229                priv->base + RCAR_IIC_ICCR);
 230         ret = sh_irq_dte_with_tack(dev);
 231         rcar_iic_finish(dev);
 232
 233         return ret;
 234 }
 235
 236 static int rcar_iic_probe(struct udevice *dev)
 237 {
 238         struct rcar_iic_priv *priv = dev_get_priv(dev);
 239         int ret;
 240
 241         priv->base = dev_read_addr_ptr(dev);
 242
 243         ret = clk_get_by_index(dev, 0, &priv->clk);
 244         if (ret)
 245                 return ret;
 246
 247         ret = clk_enable(&priv->clk);
 248         if (ret)
 249                 return ret;
 250
 251         rcar_iic_finish(dev);
 252
 253         return rcar_iic_set_speed(dev, I2C_SPEED_STANDARD_RATE);
 254 }
 255
 256 static const struct dm_i2c_ops rcar_iic_ops = {
 257         .xfer           = rcar_iic_xfer,
 258         .probe_chip     = rcar_iic_probe_chip,
 259         .set_bus_speed  = rcar_iic_set_speed,
 260 };
 261
 262 static const struct udevice_id rcar_iic_ids[] = {
 263         { .compatible = "renesas,rmobile-iic" },
 264         { }
 265 };
 266
 267 U_BOOT_DRIVER(iic_rcar) = {
 268         .name           = "iic_rcar",
 269         .id             = UCLASS_I2C,
 270         .of_match       = rcar_iic_ids,
 271         .probe          = rcar_iic_probe,
 272         .priv_auto      = sizeof(struct rcar_iic_priv),
 273         .ops            = &rcar_iic_ops,
 274 };