Baruch Siach | 4a7a082 | 2015-03-19 13:16:46 +0200 | [diff] [blame] | 1 | /* |
| 2 | * I2C bus driver for Conexant Digicolor SoCs |
| 3 | * |
| 4 | * Author: Baruch Siach <baruch@tkos.co.il> |
| 5 | * |
| 6 | * Copyright (C) 2015 Paradox Innovation Ltd. |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License version 2 as |
| 10 | * published by the Free Software Foundation. |
| 11 | */ |
| 12 | |
| 13 | #include <linux/clk.h> |
| 14 | #include <linux/completion.h> |
Wolfram Sang | 4c8979b | 2015-04-22 10:16:11 +0200 | [diff] [blame] | 15 | #include <linux/delay.h> |
Baruch Siach | 4a7a082 | 2015-03-19 13:16:46 +0200 | [diff] [blame] | 16 | #include <linux/i2c.h> |
| 17 | #include <linux/interrupt.h> |
| 18 | #include <linux/io.h> |
Baruch Siach | 4a7a082 | 2015-03-19 13:16:46 +0200 | [diff] [blame] | 19 | #include <linux/kernel.h> |
| 20 | #include <linux/module.h> |
| 21 | #include <linux/of.h> |
| 22 | #include <linux/platform_device.h> |
| 23 | |
| 24 | #define DEFAULT_FREQ 100000 |
| 25 | #define TIMEOUT_MS 100 |
| 26 | |
| 27 | #define II_CONTROL 0x0 |
| 28 | #define II_CONTROL_LOCAL_RESET BIT(0) |
| 29 | |
| 30 | #define II_CLOCKTIME 0x1 |
| 31 | |
| 32 | #define II_COMMAND 0x2 |
| 33 | #define II_CMD_START 1 |
| 34 | #define II_CMD_RESTART 2 |
| 35 | #define II_CMD_SEND_ACK 3 |
| 36 | #define II_CMD_GET_ACK 6 |
| 37 | #define II_CMD_GET_NOACK 7 |
| 38 | #define II_CMD_STOP 10 |
| 39 | #define II_COMMAND_GO BIT(7) |
| 40 | #define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3) |
| 41 | #define II_CMD_STATUS_NORMAL 0 |
| 42 | #define II_CMD_STATUS_ACK_GOOD 1 |
| 43 | #define II_CMD_STATUS_ACK_BAD 2 |
| 44 | #define II_CMD_STATUS_ABORT 3 |
| 45 | |
| 46 | #define II_DATA 0x3 |
| 47 | #define II_INTFLAG_CLEAR 0x8 |
| 48 | #define II_INTENABLE 0xa |
| 49 | |
| 50 | struct dc_i2c { |
| 51 | struct i2c_adapter adap; |
| 52 | struct device *dev; |
| 53 | void __iomem *regs; |
| 54 | struct clk *clk; |
| 55 | unsigned int frequency; |
| 56 | |
| 57 | struct i2c_msg *msg; |
| 58 | unsigned int msgbuf_ptr; |
| 59 | int last; |
| 60 | spinlock_t lock; |
| 61 | struct completion done; |
| 62 | int state; |
| 63 | int error; |
| 64 | }; |
| 65 | |
| 66 | enum { |
| 67 | STATE_IDLE, |
| 68 | STATE_START, |
| 69 | STATE_ADDR, |
| 70 | STATE_WRITE, |
| 71 | STATE_READ, |
| 72 | STATE_STOP, |
| 73 | }; |
| 74 | |
| 75 | static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd) |
| 76 | { |
| 77 | writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND); |
| 78 | } |
| 79 | |
| 80 | static u8 dc_i2c_addr_cmd(struct i2c_msg *msg) |
| 81 | { |
| 82 | u8 addr = (msg->addr & 0x7f) << 1; |
| 83 | |
| 84 | if (msg->flags & I2C_M_RD) |
| 85 | addr |= 1; |
| 86 | |
| 87 | return addr; |
| 88 | } |
| 89 | |
| 90 | static void dc_i2c_data(struct dc_i2c *i2c, u8 data) |
| 91 | { |
| 92 | writeb_relaxed(data, i2c->regs + II_DATA); |
| 93 | } |
| 94 | |
| 95 | static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte) |
| 96 | { |
| 97 | dc_i2c_data(i2c, byte); |
| 98 | dc_i2c_cmd(i2c, II_CMD_SEND_ACK); |
| 99 | } |
| 100 | |
| 101 | static void dc_i2c_write_buf(struct dc_i2c *i2c) |
| 102 | { |
| 103 | dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]); |
| 104 | } |
| 105 | |
| 106 | static void dc_i2c_next_read(struct dc_i2c *i2c) |
| 107 | { |
| 108 | bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len); |
| 109 | |
| 110 | dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK); |
| 111 | } |
| 112 | |
| 113 | static void dc_i2c_stop(struct dc_i2c *i2c) |
| 114 | { |
| 115 | i2c->state = STATE_STOP; |
| 116 | if (i2c->last) |
| 117 | dc_i2c_cmd(i2c, II_CMD_STOP); |
| 118 | else |
| 119 | complete(&i2c->done); |
| 120 | } |
| 121 | |
| 122 | static u8 dc_i2c_read_byte(struct dc_i2c *i2c) |
| 123 | { |
| 124 | return readb_relaxed(i2c->regs + II_DATA); |
| 125 | } |
| 126 | |
| 127 | static void dc_i2c_read_buf(struct dc_i2c *i2c) |
| 128 | { |
| 129 | i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c); |
| 130 | dc_i2c_next_read(i2c); |
| 131 | } |
| 132 | |
| 133 | static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable) |
| 134 | { |
| 135 | if (enable) |
| 136 | writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR); |
| 137 | writeb_relaxed(!!enable, i2c->regs + II_INTENABLE); |
| 138 | } |
| 139 | |
| 140 | static int dc_i2c_cmd_status(struct dc_i2c *i2c) |
| 141 | { |
| 142 | u8 cmd = readb_relaxed(i2c->regs + II_COMMAND); |
| 143 | |
| 144 | return II_COMMAND_COMPLETION_STATUS(cmd); |
| 145 | } |
| 146 | |
| 147 | static void dc_i2c_start_msg(struct dc_i2c *i2c, int first) |
| 148 | { |
| 149 | struct i2c_msg *msg = i2c->msg; |
| 150 | |
| 151 | if (!(msg->flags & I2C_M_NOSTART)) { |
| 152 | i2c->state = STATE_START; |
| 153 | dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART); |
| 154 | } else if (msg->flags & I2C_M_RD) { |
| 155 | i2c->state = STATE_READ; |
| 156 | dc_i2c_next_read(i2c); |
| 157 | } else { |
| 158 | i2c->state = STATE_WRITE; |
| 159 | dc_i2c_write_buf(i2c); |
| 160 | } |
| 161 | } |
| 162 | |
| 163 | static irqreturn_t dc_i2c_irq(int irq, void *dev_id) |
| 164 | { |
| 165 | struct dc_i2c *i2c = dev_id; |
| 166 | int cmd_status = dc_i2c_cmd_status(i2c); |
| 167 | unsigned long flags; |
| 168 | u8 addr_cmd; |
| 169 | |
| 170 | writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR); |
| 171 | |
| 172 | spin_lock_irqsave(&i2c->lock, flags); |
| 173 | |
| 174 | if (cmd_status == II_CMD_STATUS_ACK_BAD |
| 175 | || cmd_status == II_CMD_STATUS_ABORT) { |
| 176 | i2c->error = -EIO; |
| 177 | complete(&i2c->done); |
| 178 | goto out; |
| 179 | } |
| 180 | |
| 181 | switch (i2c->state) { |
| 182 | case STATE_START: |
| 183 | addr_cmd = dc_i2c_addr_cmd(i2c->msg); |
| 184 | dc_i2c_write_byte(i2c, addr_cmd); |
| 185 | i2c->state = STATE_ADDR; |
| 186 | break; |
| 187 | case STATE_ADDR: |
| 188 | if (i2c->msg->flags & I2C_M_RD) { |
| 189 | dc_i2c_next_read(i2c); |
| 190 | i2c->state = STATE_READ; |
| 191 | break; |
| 192 | } |
| 193 | i2c->state = STATE_WRITE; |
| 194 | /* fall through */ |
| 195 | case STATE_WRITE: |
| 196 | if (i2c->msgbuf_ptr < i2c->msg->len) |
| 197 | dc_i2c_write_buf(i2c); |
| 198 | else |
| 199 | dc_i2c_stop(i2c); |
| 200 | break; |
| 201 | case STATE_READ: |
| 202 | if (i2c->msgbuf_ptr < i2c->msg->len) |
| 203 | dc_i2c_read_buf(i2c); |
| 204 | else |
| 205 | dc_i2c_stop(i2c); |
| 206 | break; |
| 207 | case STATE_STOP: |
| 208 | i2c->state = STATE_IDLE; |
| 209 | complete(&i2c->done); |
| 210 | break; |
| 211 | } |
| 212 | |
| 213 | out: |
| 214 | spin_unlock_irqrestore(&i2c->lock, flags); |
| 215 | return IRQ_HANDLED; |
| 216 | } |
| 217 | |
| 218 | static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first, |
| 219 | int last) |
| 220 | { |
| 221 | unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS); |
| 222 | unsigned long flags; |
| 223 | |
| 224 | spin_lock_irqsave(&i2c->lock, flags); |
| 225 | i2c->msg = msg; |
| 226 | i2c->msgbuf_ptr = 0; |
| 227 | i2c->last = last; |
| 228 | i2c->error = 0; |
| 229 | |
| 230 | reinit_completion(&i2c->done); |
| 231 | dc_i2c_set_irq(i2c, 1); |
| 232 | dc_i2c_start_msg(i2c, first); |
| 233 | spin_unlock_irqrestore(&i2c->lock, flags); |
| 234 | |
| 235 | timeout = wait_for_completion_timeout(&i2c->done, timeout); |
| 236 | dc_i2c_set_irq(i2c, 0); |
| 237 | if (timeout == 0) { |
| 238 | i2c->state = STATE_IDLE; |
| 239 | return -ETIMEDOUT; |
| 240 | } |
| 241 | |
| 242 | if (i2c->error) |
| 243 | return i2c->error; |
| 244 | |
| 245 | return 0; |
| 246 | } |
| 247 | |
| 248 | static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) |
| 249 | { |
| 250 | struct dc_i2c *i2c = adap->algo_data; |
| 251 | int i, ret; |
| 252 | |
| 253 | for (i = 0; i < num; i++) { |
| 254 | ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1); |
| 255 | if (ret) |
| 256 | return ret; |
| 257 | } |
| 258 | |
| 259 | return num; |
| 260 | } |
| 261 | |
| 262 | static int dc_i2c_init_hw(struct dc_i2c *i2c) |
| 263 | { |
| 264 | unsigned long clk_rate = clk_get_rate(i2c->clk); |
| 265 | unsigned int clocktime; |
| 266 | |
| 267 | writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL); |
| 268 | udelay(100); |
| 269 | writeb_relaxed(0, i2c->regs + II_CONTROL); |
| 270 | udelay(100); |
| 271 | |
| 272 | clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency); |
| 273 | if (clocktime < 1 || clocktime > 0xff) { |
| 274 | dev_err(i2c->dev, "can't set bus speed of %u Hz\n", |
| 275 | i2c->frequency); |
| 276 | return -EINVAL; |
| 277 | } |
| 278 | writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME); |
| 279 | |
| 280 | return 0; |
| 281 | } |
| 282 | |
| 283 | static u32 dc_i2c_func(struct i2c_adapter *adap) |
| 284 | { |
| 285 | return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART; |
| 286 | } |
| 287 | |
| 288 | static const struct i2c_algorithm dc_i2c_algorithm = { |
| 289 | .master_xfer = dc_i2c_xfer, |
| 290 | .functionality = dc_i2c_func, |
| 291 | }; |
| 292 | |
| 293 | static int dc_i2c_probe(struct platform_device *pdev) |
| 294 | { |
| 295 | struct device_node *np = pdev->dev.of_node; |
| 296 | struct dc_i2c *i2c; |
| 297 | struct resource *r; |
| 298 | int ret = 0, irq; |
| 299 | |
| 300 | i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL); |
| 301 | if (!i2c) |
| 302 | return -ENOMEM; |
| 303 | |
| 304 | if (of_property_read_u32(pdev->dev.of_node, "clock-frequency", |
| 305 | &i2c->frequency)) |
| 306 | i2c->frequency = DEFAULT_FREQ; |
| 307 | |
| 308 | i2c->dev = &pdev->dev; |
| 309 | platform_set_drvdata(pdev, i2c); |
| 310 | |
| 311 | spin_lock_init(&i2c->lock); |
| 312 | init_completion(&i2c->done); |
| 313 | |
| 314 | i2c->clk = devm_clk_get(&pdev->dev, NULL); |
| 315 | if (IS_ERR(i2c->clk)) |
| 316 | return PTR_ERR(i2c->clk); |
| 317 | |
| 318 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); |
| 319 | i2c->regs = devm_ioremap_resource(&pdev->dev, r); |
| 320 | if (IS_ERR(i2c->regs)) |
| 321 | return PTR_ERR(i2c->regs); |
| 322 | |
| 323 | irq = platform_get_irq(pdev, 0); |
| 324 | if (irq < 0) |
| 325 | return irq; |
| 326 | |
| 327 | ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0, |
| 328 | dev_name(&pdev->dev), i2c); |
| 329 | if (ret < 0) |
| 330 | return ret; |
| 331 | |
| 332 | strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter", |
| 333 | sizeof(i2c->adap.name)); |
| 334 | i2c->adap.owner = THIS_MODULE; |
| 335 | i2c->adap.algo = &dc_i2c_algorithm; |
| 336 | i2c->adap.dev.parent = &pdev->dev; |
| 337 | i2c->adap.dev.of_node = np; |
| 338 | i2c->adap.algo_data = i2c; |
| 339 | |
| 340 | ret = dc_i2c_init_hw(i2c); |
| 341 | if (ret) |
| 342 | return ret; |
| 343 | |
| 344 | ret = clk_prepare_enable(i2c->clk); |
| 345 | if (ret < 0) |
| 346 | return ret; |
| 347 | |
| 348 | ret = i2c_add_adapter(&i2c->adap); |
| 349 | if (ret < 0) { |
Wei Yongjun | 68d85d0 | 2016-10-29 16:31:17 +0000 | [diff] [blame] | 350 | clk_disable_unprepare(i2c->clk); |
Baruch Siach | 4a7a082 | 2015-03-19 13:16:46 +0200 | [diff] [blame] | 351 | return ret; |
| 352 | } |
| 353 | |
| 354 | return 0; |
| 355 | } |
| 356 | |
| 357 | static int dc_i2c_remove(struct platform_device *pdev) |
| 358 | { |
| 359 | struct dc_i2c *i2c = platform_get_drvdata(pdev); |
| 360 | |
| 361 | i2c_del_adapter(&i2c->adap); |
| 362 | clk_disable_unprepare(i2c->clk); |
| 363 | |
| 364 | return 0; |
| 365 | } |
| 366 | |
| 367 | static const struct of_device_id dc_i2c_match[] = { |
| 368 | { .compatible = "cnxt,cx92755-i2c" }, |
| 369 | { }, |
| 370 | }; |
Javier Martinez Canillas | 60a951a | 2016-10-18 18:01:48 -0300 | [diff] [blame] | 371 | MODULE_DEVICE_TABLE(of, dc_i2c_match); |
Baruch Siach | 4a7a082 | 2015-03-19 13:16:46 +0200 | [diff] [blame] | 372 | |
| 373 | static struct platform_driver dc_i2c_driver = { |
| 374 | .probe = dc_i2c_probe, |
| 375 | .remove = dc_i2c_remove, |
| 376 | .driver = { |
| 377 | .name = "digicolor-i2c", |
| 378 | .of_match_table = dc_i2c_match, |
| 379 | }, |
| 380 | }; |
| 381 | module_platform_driver(dc_i2c_driver); |
| 382 | |
| 383 | MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>"); |
| 384 | MODULE_DESCRIPTION("Conexant Digicolor I2C master driver"); |
| 385 | MODULE_LICENSE("GPL v2"); |