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          100
  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;    /* Current I2C message */
  48         bool last;              /* Whether the message is the last */
  49         uint count;             /* Number of bytes in the current transfer */
  50         uint pos;               /* Position of current transfer in message */
  51         u32 tokens[2];          /* Sequence of tokens to be written */
  52         uint num_tokens;        /* Number of tokens to be written */
  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 /*
  73  * Retrieve data for the current transfer (which can be at most 8
  74  * bytes) from the device internal buffer.
  75  */
  76 static void meson_i2c_get_data(struct meson_i2c *i2c, u8 *buf, int len)
  77 {
  78         u32 rdata0, rdata1;
  79         int i;
  80
  81         rdata0 = readl(&i2c->regs->tok_rdata0);
  82         rdata1 = readl(&i2c->regs->tok_rdata1);
  83
  84         debug("meson i2c: read data %08x %08x len %d\n", rdata0, rdata1, len);
  85
  86         for (i = 0; i < min(4, len); i++)
  87                 *buf++ = (rdata0 >> i * 8) & 0xff;
  88
  89         for (i = 4; i < min(8, len); i++)
  90                 *buf++ = (rdata1 >> (i - 4) * 8) & 0xff;
  91 }
  92
  93 /*
  94  * Write data for the current transfer (which can be at most 8 bytes)
  95  * to the device internal buffer.
  96  */
  97 static void meson_i2c_put_data(struct meson_i2c *i2c, u8 *buf, int len)
  98 {
  99         u32 wdata0 = 0, wdata1 = 0;
 100         int i;
 101
 102         for (i = 0; i < min(4, len); i++)
 103                 wdata0 |= *buf++ << (i * 8);
 104
 105         for (i = 4; i < min(8, len); i++)
 106                 wdata1 |= *buf++ << ((i - 4) * 8);
 107
 108         writel(wdata0, &i2c->regs->tok_wdata0);
 109         writel(wdata1, &i2c->regs->tok_wdata1);
 110
 111         debug("meson i2c: write data %08x %08x len %d\n", wdata0, wdata1, len);
 112 }
 113
 114 /*
 115  * Prepare the next transfer: pick the next 8 bytes in the remaining
 116  * part of message and write tokens and data (if needed) to the
 117  * device.
 118  */
 119 static void meson_i2c_prepare_xfer(struct meson_i2c *i2c)
 120 {
 121         bool write = !(i2c->msg->flags & I2C_M_RD);
 122         int i;
 123
 124         i2c->count = min(i2c->msg->len - i2c->pos, 8u);
 125
 126         for (i = 0; i + 1 < i2c->count; i++)
 127                 meson_i2c_add_token(i2c, TOKEN_DATA);
 128
 129         if (i2c->count) {
 130                 if (write || i2c->pos + i2c->count < i2c->msg->len)
 131                         meson_i2c_add_token(i2c, TOKEN_DATA);
 132                 else
 133                         meson_i2c_add_token(i2c, TOKEN_DATA_LAST);
 134         }
 135
 136         if (write)
 137                 meson_i2c_put_data(i2c, i2c->msg->buf + i2c->pos, i2c->count);
 138
 139         if (i2c->last && i2c->pos + i2c->count >= i2c->msg->len)
 140                 meson_i2c_add_token(i2c, TOKEN_STOP);
 141
 142         writel(i2c->tokens[0], &i2c->regs->tok_list0);
 143         writel(i2c->tokens[1], &i2c->regs->tok_list1);
 144 }
 145
 146 static void meson_i2c_do_start(struct meson_i2c *i2c, struct i2c_msg *msg)
 147 {
 148         int token;
 149
 150         token = (msg->flags & I2C_M_RD) ? TOKEN_SLAVE_ADDR_READ :
 151                 TOKEN_SLAVE_ADDR_WRITE;
 152
 153         writel(msg->addr << 1, &i2c->regs->slave_addr);
 154         meson_i2c_add_token(i2c, TOKEN_START);
 155         meson_i2c_add_token(i2c, token);
 156 }
 157
 158 static int meson_i2c_xfer_msg(struct meson_i2c *i2c, struct i2c_msg *msg,
 159                               int last)
 160 {
 161         ulong start;
 162
 163         debug("meson i2c: %s addr %u len %u\n",
 164               (msg->flags & I2C_M_RD) ? "read" : "write",
 165               msg->addr, msg->len);
 166
 167         i2c->msg = msg;
 168         i2c->last = last;
 169         i2c->pos = 0;
 170         i2c->count = 0;
 171
 172         meson_i2c_reset_tokens(i2c);
 173         meson_i2c_do_start(i2c, msg);
 174
 175         do {
 176                 meson_i2c_prepare_xfer(i2c);
 177
 178                 /* start the transfer */
 179                 setbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 180                 start = get_timer(0);
 181                 while (readl(&i2c->regs->ctrl) & REG_CTRL_STATUS) {
 182                         if (get_timer(start) > I2C_TIMEOUT_MS) {
 183                                 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 184                                 debug("meson i2c: timeout\n");
 185                                 return -ETIMEDOUT;
 186                         }
 187                         udelay(1);
 188                 }
 189                 meson_i2c_reset_tokens(i2c);
 190                 clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 191
 192                 if (readl(&i2c->regs->ctrl) & REG_CTRL_ERROR) {
 193                         debug("meson i2c: error\n");
 194                         return -EREMOTEIO;
 195                 }
 196
 197                 if ((msg->flags & I2C_M_RD) && i2c->count) {
 198                         meson_i2c_get_data(i2c, i2c->msg->buf + i2c->pos,
 199                                            i2c->count);
 200                 }
 201                 i2c->pos += i2c->count;
 202         } while (i2c->pos < msg->len);
 203
 204         return 0;
 205 }
 206
 207 static int meson_i2c_xfer(struct udevice *bus, struct i2c_msg *msg,
 208                           int nmsgs)
 209 {
 210         struct meson_i2c *i2c = dev_get_priv(bus);
 211         int i, ret = 0;
 212
 213         for (i = 0; i < nmsgs; i++) {
 214                 ret = meson_i2c_xfer_msg(i2c, msg + i, i == nmsgs - 1);
 215                 if (ret)
 216                         return ret;
 217         }
 218
 219         return 0;
 220 }
 221
 222 static int meson_i2c_set_bus_speed(struct udevice *bus, unsigned int speed)
 223 {
 224         struct meson_i2c *i2c = dev_get_priv(bus);
 225         unsigned int clk_rate = MESON_I2C_CLK_RATE;
 226         unsigned int div;
 227
 228         div = DIV_ROUND_UP(clk_rate, speed * 4);
 229
 230         /* clock divider has 12 bits */
 231         if (div >= (1 << 12)) {
 232                 debug("meson i2c: requested bus frequency too low\n");
 233                 div = (1 << 12) - 1;
 234         }
 235
 236         clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIV_MASK,
 237                         (div & GENMASK(9, 0)) << REG_CTRL_CLKDIV_SHIFT);
 238
 239         clrsetbits_le32(&i2c->regs->ctrl, REG_CTRL_CLKDIVEXT_MASK,
 240                         (div >> 10) << REG_CTRL_CLKDIVEXT_SHIFT);
 241
 242         debug("meson i2c: set clk %u, src %u, div %u\n", speed, clk_rate, div);
 243
 244         return 0;
 245 }
 246
 247 static int meson_i2c_probe(struct udevice *bus)
 248 {
 249         struct meson_i2c *i2c = dev_get_priv(bus);
 250
 251         i2c->regs = dev_read_addr_ptr(bus);
 252         clrbits_le32(&i2c->regs->ctrl, REG_CTRL_START);
 253
 254         return 0;
 255 }
 256
 257 static const struct dm_i2c_ops meson_i2c_ops = {
 258         .xfer          = meson_i2c_xfer,
 259         .set_bus_speed = meson_i2c_set_bus_speed,
 260 };
 261
 262 static const struct udevice_id meson_i2c_ids[] = {
 263         { .compatible = "amlogic,meson6-i2c" },
 264         { .compatible = "amlogic,meson-gx-i2c" },
 265         { .compatible = "amlogic,meson-gxbb-i2c" },
 266         { }
 267 };
 268
 269 U_BOOT_DRIVER(i2c_meson) = {
 270         .name = "i2c_meson",
 271         .id   = UCLASS_I2C,
 272         .of_match = meson_i2c_ids,
 273         .probe = meson_i2c_probe,
 274         .priv_auto_alloc_size = sizeof(struct meson_i2c),
 275         .ops = &meson_i2c_ops,
 276 };