drivers/i2c/meson_i2c.c

   1 /*
   2  * (C) Copyright 2017 - Beniamino Galvani <b.galvani@gmail.com>
   3  *
   4  * SPDX-License-Identifier:     GPL-2.0+
   5  */
   6 #include <common.h>
   7 #include <asm/arch/i2c.h>
   8 #include <asm/io.h>
   9 #include <dm.h>
  10 #include <i2c.h>
  11
  12 #define I2C_TIMEOUT_MS          500
  13
  14 /* Control register fields */
  15 #define REG_CTRL_START          BIT(0)
  16 #define REG_CTRL_ACK_IGNORE     BIT(1)
  17 #define REG_CTRL_STATUS         BIT(2)
  18 #define REG_CTRL_ERROR          BIT(3)
  19 #define REG_CTRL_CLKDIV_SHIFT   12
  20 #define REG_CTRL_CLKDIV_MASK    GENMASK(21, 12)
  21 #define REG_CTRL_CLKDIVEXT_SHIFT 28
  22 #define REG_CTRL_CLKDIVEXT_MASK GENMASK(29, 28)
  23
  24 enum {
  25         TOKEN_END = 0,
  26         TOKEN_START,
  27         TOKEN_SLAVE_ADDR_WRITE,
  28         TOKEN_SLAVE_ADDR_READ,
  29         TOKEN_DATA,
  30         TOKEN_DATA_LAST,
  31         TOKEN_STOP,
  32 };
  33
  34 struct i2c_regs {
  35         u32 ctrl;
  36         u32 slave_addr;
  37         u32 tok_list0;
  38         u32 tok_list1;
  39         u32 tok_wdata0;
  40         u32 tok_wdata1;
  41         u32 tok_rdata0;
  42         u32 tok_rdata1;
  43 };
  44
  45 struct meson_i2c {
  46         struct i2c_regs *regs;
  47         struct i2c_msg *msg;
  48         bool last;
  49         uint count;
  50         uint pos;
  51         u32 tokens[2];
  52         uint num_tokens;
  53 };
  54
  55 static void meson_i2c_reset_tokens(struct meson_i2c *i2c)
  56 {
  57         i2c->tokens[0] = 0;
  58         i2c->tokens[1] = 0;
  59         i2c->num_tokens = 0;
  60 }
  61
  62 static void meson_i2c_add_token(struct meson_i2c *i2c, int token)
  63 {
  64         if (i2c->num_tokens < 8)
  65                 i2c->tokens[0] |= (token & 0xf) << (i2c->num_tokens * 4);
  66         else
  67                 i2c->tokens[1] |= (token & 0xf) << ((i2c->num_tokens % 8) * 4);
  68
  69         i2c->num_tokens++;
  70 }
  71
  72 static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
  73 {
  74         u32 rdata0, rdata1;
  75         int i;
  76
  77         rdata0 = readl(&i2c->regs->tok_rdata0);
  78         rdata1 = readl(&i2c->regs->tok_rdata1);
  79
  80         debug("meson i2c: read data %08x %08x len %d\n", rdata0, rdata1, len);
  81
  82         for (i = 0; i < min(4, len); i++)
  83                 *buf++ = (rdata0 >> i * 8) & 0xff;
  84
  85         for (i = 4; i < min(8, len); i++)
  86                 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
  87 }
  88
  89 static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
  90 {
  91         u32 wdata0 = 0, wdata1 = 0;
  92         int i;
  93
  94         for (i = 0; i < min(4, len); i++)
  95                 wdata0 |= *buf++ << (i * 8);
  96
  97         for (i = 4; i < min(8, len); i++)
  98                 wdata1 |= *buf++ << ((i - 4) * 8);
  99
 100         writel(wdata0, &i2c->regs->tok_wdata0);
 101         writel(wdata1, &i2c->regs->tok_wdata1);
 102
 103         debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len);
 104 }
 105
 106 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 107 {
 108         bool write = !(i2c->msg->flags & I2C_M_RD);
 109         int i;
 110
 111         i2c->count = min(i2c->msg->len - i2c->pos, 8u);
 112
 113         for (i = 0; i + 1 < i2c->count; i++)
 114                 meson_i2c_add_token(i2c, TOKEN_DATA);
 115
 116         if (i2c->count) {
 117                 if (write || i2c->pos + i2c->count < i2c->msg->len)
 118                         meson_i2c_add_token(i2c, TOKEN_DATA);
 119                 else
 120                         meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
 121         }
 122
 123         if (write)
 124                 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
 125
 126         if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 127                 meson_i2c_add_token(i2c, TOKEN_STOP);
 128
 129         writel(i2c->tokens[0], &i2c->regs->tok_list0);
 130         writel(i2c->tokens[1], &i2c->regs->tok_list1);
 131 }
 132
 133 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
 134 {
 135         int token;
 136
 137         token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
 138                 TOKEN_SLAVE_ADDR_WRITE;
 139
 140         writel(msg->addr << 1, &i2c->regs->slave_addr);
 141         meson_i2c_add_token(i2c, TOKEN_START);
 142         meson_i2c_add_token(i2c, token);
 143 }
 144
 145 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
 146                               int last)
 147 {
 148         ulong start;
 149
 150         debug("meson i2c: %s addr %u len %u\n",
 151               (msg->flags & I2C_M_RD) ? "read" : "write",
 152               msg->addr, msg->len);
 153
 154         i2c->msg = msg;
 155         i2c->last = last;
 156         i2c->pos = 0;
 157         i2c->count = 0;
 158
 159         meson_i2c_reset_tokens(i2c);
 160         meson_i2c_do_start(i2c, msg);
 161
 162         do {
 163                 meson_i2c_prepare_xfer(i2c);
 164
 165                 /* start the transfer */
 166                 setbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 167                 start = get_timer(0);
 168                 while (readl(&i2c->regs->ctrl) & REG_CTRL_STATUS) {
 169                         if (get_timer(start) > I2C_TIMEOUT_MS) {
 170                                 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 171                                 debug("meson i2c: timeout\n");
 172                                 return -ETIMEDOUT;
 173                         }
 174                         udelay(1);
 175                 }
 176                 meson_i2c_reset_tokens(i2c);
 177                 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 178
 179                 if (readl(&i2c->regs->ctrl) & REG_CTRL_ERROR) {
 180                         debug("meson i2c: error\n");
 181                         return -ENXIO;
 182                 }
 183
 184                 if ((msg->flags & I2C_M_RD) && i2c->count) {
 185                         meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
 186                                            i2c->count);
 187                 }
 188                 i2c->pos += i2c->count;
 189         } while (i2c->pos < msg->len);
 190
 191         return 0;
 192 }
 193
 194 static int meson_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
 195                           int nmsgs)
 196 {
 197         struct meson_i2c *i2c = dev_get_priv(bus);
 198         int i, ret = 0;
 199
 200         for (i = 0; i < nmsgs; i++) {
 201                 ret = meson_i2c_xfer_msg(i2c, msg + i, i == nmsgs - 1);
 202                 if (ret)
 203                         return -EREMOTEIO;
 204         }
 205
 206         return 0;
 207 }
 208
 209 static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
 210 {
 211         struct meson_i2c *i2c = dev_get_priv(bus);
 212         unsigned int clk_rate = MESON_I2C_CLK_RATE;
 213         unsigned int div;
 214
 215         div = DIV_ROUND_UP(clk_rate, speed * 4);
 216
 217         /* clock divider has 12 bits */
 218         if (div >= (1 << 12)) {
 219                 debug("meson i2c: requested bus frequency too low\n");
 220                 div = (1 << 12) - 1;
 221         }
 222
 223         clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
 224                         (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
 225
 226         clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIVEXT_MASK,
 227                         (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 228
 229         debug("meson i2c: set clk %u, src %u, div %u\n", speed, clk_rate, div);
 230
 231         return 0;
 232 }
 233
 234 static int meson_i2c_probe(struct udevice *bus)
 235 {
 236         struct meson_i2c *i2c = dev_get_priv(bus);
 237
 238         i2c->regs = dev_read_addr_ptr(bus);
 239         clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 240
 241         return 0;
 242 }
 243
 244 static const struct dm_i2c_ops meson_i2c_ops = {
 245         .xfer          = meson_i2c_xfer,
 246         .set_bus_speed = meson_i2c_set_bus_speed,
 247 };
 248
 249 static const struct udevice_id meson_i2c_ids[] = {
 250         { .compatible = "amlogic,meson6-i2c" },
 251         { .compatible = "amlogic,meson-gx-i2c" },
 252         { .compatible = "amlogic,meson-gxbb-i2c" },
 253         { }
 254 };
 255
 256 U_BOOT_DRIVER(i2c_meson) = {
 257         .name = "i2c_meson",
 258         .id   = UCLASS_I2C,
 259         .of_match = meson_i2c_ids,
 260         .probe = meson_i2c_probe,
 261         .priv_auto_alloc_size = sizeof(struct meson_i2c),
 262         .ops = &meson_i2c_ops,
 263 };