drivers/ssbi/ssbi.c

   1 /* Copyright (c) 2009-2013, The Linux Foundation. All rights reserved.
   2  * Copyright (c) 2010, Google Inc.
   3  *
   4  * Original authors: Code Aurora Forum
   5  *
   6  * Author: Dima Zavin <dima@android.com>
   7  *  - Largely rewritten from original to not be an i2c driver.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 and
  11  * only version 2 as published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  */
  18
  19 #define pr_fmt(fmt) "%s: " fmt, __func__
  20
  21 #include <linux/delay.h>
  22 #include <linux/err.h>
  23 #include <linux/io.h>
  24 #include <linux/kernel.h>
  25 #include <linux/platform_device.h>
  26 #include <linux/slab.h>
  27 #include <linux/ssbi.h>
  28 #include <linux/module.h>
  29 #include <linux/of.h>
  30 #include <linux/of_device.h>
  31
  32 /* SSBI 2.0 controller registers */
  33 #define SSBI2_CMD                       0x0008
  34 #define SSBI2_RD                        0x0010
  35 #define SSBI2_STATUS                    0x0014
  36 #define SSBI2_MODE2                     0x001C
  37
  38 /* SSBI_CMD fields */
  39 #define SSBI_CMD_RDWRN                  (1 << 24)
  40
  41 /* SSBI_STATUS fields */
  42 #define SSBI_STATUS_RD_READY            (1 << 2)
  43 #define SSBI_STATUS_READY               (1 << 1)
  44 #define SSBI_STATUS_MCHN_BUSY           (1 << 0)
  45
  46 /* SSBI_MODE2 fields */
  47 #define SSBI_MODE2_REG_ADDR_15_8_SHFT   0x04
  48 #define SSBI_MODE2_REG_ADDR_15_8_MASK   (0x7f << SSBI_MODE2_REG_ADDR_15_8_SHFT)
  49
  50 #define SET_SSBI_MODE2_REG_ADDR_15_8(MD, AD) \
  51         (((MD) & 0x0F) | ((((AD) >> 8) << SSBI_MODE2_REG_ADDR_15_8_SHFT) & \
  52         SSBI_MODE2_REG_ADDR_15_8_MASK))
  53
  54 /* SSBI PMIC Arbiter command registers */
  55 #define SSBI_PA_CMD                     0x0000
  56 #define SSBI_PA_RD_STATUS               0x0004
  57
  58 /* SSBI_PA_CMD fields */
  59 #define SSBI_PA_CMD_RDWRN               (1 << 24)
  60 #define SSBI_PA_CMD_ADDR_MASK           0x7fff /* REG_ADDR_7_0, REG_ADDR_8_14*/
  61
  62 /* SSBI_PA_RD_STATUS fields */
  63 #define SSBI_PA_RD_STATUS_TRANS_DONE    (1 << 27)
  64 #define SSBI_PA_RD_STATUS_TRANS_DENIED  (1 << 26)
  65
  66 #define SSBI_TIMEOUT_US                 100
  67
  68 struct ssbi {
  69         struct device           *slave;
  70         void __iomem            *base;
  71         spinlock_t              lock;
  72         enum ssbi_controller_type controller_type;
  73         int (*read)(struct ssbi *, u16 addr, u8 *buf, int len);
  74         int (*write)(struct ssbi *, u16 addr, u8 *buf, int len);
  75 };
  76
  77 #define to_ssbi(dev)    platform_get_drvdata(to_platform_device(dev))
  78
  79 static inline u32 ssbi_readl(struct ssbi *ssbi, u32 reg)
  80 {
  81         return readl(ssbi->base + reg);
  82 }
  83
  84 static inline void ssbi_writel(struct ssbi *ssbi, u32 val, u32 reg)
  85 {
  86         writel(val, ssbi->base + reg);
  87 }
  88
  89 /*
  90  * Via private exchange with one of the original authors, the hardware
  91  * should generally finish a transaction in about 5us.  The worst
  92  * case, is when using the arbiter and both other CPUs have just
  93  * started trying to use the SSBI bus will result in a time of about
  94  * 20us.  It should never take longer than this.
  95  *
  96  * As such, this wait merely spins, with a udelay.
  97  */
  98 static int ssbi_wait_mask(struct ssbi *ssbi, u32 set_mask, u32 clr_mask)
  99 {
 100         u32 timeout = SSBI_TIMEOUT_US;
 101         u32 val;
 102
 103         while (timeout--) {
 104                 val = ssbi_readl(ssbi, SSBI2_STATUS);
 105                 if (((val & set_mask) == set_mask) && ((val & clr_mask) == 0))
 106                         return 0;
 107                 udelay(1);
 108         }
 109
 110         return -ETIMEDOUT;
 111 }
 112
 113 static int
 114 ssbi_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 115 {
 116         u32 cmd = SSBI_CMD_RDWRN | ((addr & 0xff) << 16);
 117         int ret = 0;
 118
 119         if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
 120                 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
 121                 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
 122                 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
 123         }
 124
 125         while (len) {
 126                 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
 127                 if (ret)
 128                         goto err;
 129
 130                 ssbi_writel(ssbi, cmd, SSBI2_CMD);
 131                 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_RD_READY, 0);
 132                 if (ret)
 133                         goto err;
 134                 *buf++ = ssbi_readl(ssbi, SSBI2_RD) & 0xff;
 135                 len--;
 136         }
 137
 138 err:
 139         return ret;
 140 }
 141
 142 static int
 143 ssbi_write_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 144 {
 145         int ret = 0;
 146
 147         if (ssbi->controller_type == MSM_SBI_CTRL_SSBI2) {
 148                 u32 mode2 = ssbi_readl(ssbi, SSBI2_MODE2);
 149                 mode2 = SET_SSBI_MODE2_REG_ADDR_15_8(mode2, addr);
 150                 ssbi_writel(ssbi, mode2, SSBI2_MODE2);
 151         }
 152
 153         while (len) {
 154                 ret = ssbi_wait_mask(ssbi, SSBI_STATUS_READY, 0);
 155                 if (ret)
 156                         goto err;
 157
 158                 ssbi_writel(ssbi, ((addr & 0xff) << 16) | *buf, SSBI2_CMD);
 159                 ret = ssbi_wait_mask(ssbi, 0, SSBI_STATUS_MCHN_BUSY);
 160                 if (ret)
 161                         goto err;
 162                 buf++;
 163                 len--;
 164         }
 165
 166 err:
 167         return ret;
 168 }
 169
 170 /*
 171  * See ssbi_wait_mask for an explanation of the time and the
 172  * busywait.
 173  */
 174 static inline int
 175 ssbi_pa_transfer(struct ssbi *ssbi, u32 cmd, u8 *data)
 176 {
 177         u32 timeout = SSBI_TIMEOUT_US;
 178         u32 rd_status = 0;
 179
 180         ssbi_writel(ssbi, cmd, SSBI_PA_CMD);
 181
 182         while (timeout--) {
 183                 rd_status = ssbi_readl(ssbi, SSBI_PA_RD_STATUS);
 184
 185                 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DENIED)
 186                         return -EPERM;
 187
 188                 if (rd_status & SSBI_PA_RD_STATUS_TRANS_DONE) {
 189                         if (data)
 190                                 *data = rd_status & 0xff;
 191                         return 0;
 192                 }
 193                 udelay(1);
 194         }
 195
 196         return -ETIMEDOUT;
 197 }
 198
 199 static int
 200 ssbi_pa_read_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 201 {
 202         u32 cmd;
 203         int ret = 0;
 204
 205         cmd = SSBI_PA_CMD_RDWRN | (addr & SSBI_PA_CMD_ADDR_MASK) << 8;
 206
 207         while (len) {
 208                 ret = ssbi_pa_transfer(ssbi, cmd, buf);
 209                 if (ret)
 210                         goto err;
 211                 buf++;
 212                 len--;
 213         }
 214
 215 err:
 216         return ret;
 217 }
 218
 219 static int
 220 ssbi_pa_write_bytes(struct ssbi *ssbi, u16 addr, u8 *buf, int len)
 221 {
 222         u32 cmd;
 223         int ret = 0;
 224
 225         while (len) {
 226                 cmd = (addr & SSBI_PA_CMD_ADDR_MASK) << 8 | *buf;
 227                 ret = ssbi_pa_transfer(ssbi, cmd, NULL);
 228                 if (ret)
 229                         goto err;
 230                 buf++;
 231                 len--;
 232         }
 233
 234 err:
 235         return ret;
 236 }
 237
 238 int ssbi_read(struct device *dev, u16 addr, u8 *buf, int len)
 239 {
 240         struct ssbi *ssbi = to_ssbi(dev);
 241         unsigned long flags;
 242         int ret;
 243
 244         spin_lock_irqsave(&ssbi->lock, flags);
 245         ret = ssbi->read(ssbi, addr, buf, len);
 246         spin_unlock_irqrestore(&ssbi->lock, flags);
 247
 248         return ret;
 249 }
 250 EXPORT_SYMBOL_GPL(ssbi_read);
 251
 252 int ssbi_write(struct device *dev, u16 addr, u8 *buf, int len)
 253 {
 254         struct ssbi *ssbi = to_ssbi(dev);
 255         unsigned long flags;
 256         int ret;
 257
 258         spin_lock_irqsave(&ssbi->lock, flags);
 259         ret = ssbi->write(ssbi, addr, buf, len);
 260         spin_unlock_irqrestore(&ssbi->lock, flags);
 261
 262         return ret;
 263 }
 264 EXPORT_SYMBOL_GPL(ssbi_write);
 265
 266 static int ssbi_probe(struct platform_device *pdev)
 267 {
 268         struct device_node *np = pdev->dev.of_node;
 269         struct resource *mem_res;
 270         struct ssbi *ssbi;
 271         int ret = 0;
 272         const char *type;
 273
 274         ssbi = kzalloc(sizeof(struct ssbi), GFP_KERNEL);
 275         if (!ssbi) {
 276                 pr_err("can not allocate ssbi_data\n");
 277                 return -ENOMEM;
 278         }
 279
 280         mem_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 281         if (!mem_res) {
 282                 pr_err("missing mem resource\n");
 283                 ret = -EINVAL;
 284                 goto err_get_mem_res;
 285         }
 286
 287         ssbi->base = ioremap(mem_res->start, resource_size(mem_res));
 288         if (!ssbi->base) {
 289                 pr_err("ioremap of 0x%p failed\n", (void *)mem_res->start);
 290                 ret = -EINVAL;
 291                 goto err_ioremap;
 292         }
 293         platform_set_drvdata(pdev, ssbi);
 294
 295         type = of_get_property(np, "qcom,controller-type", NULL);
 296         if (type == NULL) {
 297                 pr_err("Missing qcom,controller-type property\n");
 298                 ret = -EINVAL;
 299                 goto err_ssbi_controller;
 300         }
 301         dev_info(&pdev->dev, "SSBI controller type: '%s'\n", type);
 302         if (strcmp(type, "ssbi") == 0)
 303                 ssbi->controller_type = MSM_SBI_CTRL_SSBI;
 304         else if (strcmp(type, "ssbi2") == 0)
 305                 ssbi->controller_type = MSM_SBI_CTRL_SSBI2;
 306         else if (strcmp(type, "pmic-arbiter") == 0)
 307                 ssbi->controller_type = MSM_SBI_CTRL_PMIC_ARBITER;
 308         else {
 309                 pr_err("Unknown qcom,controller-type\n");
 310                 ret = -EINVAL;
 311                 goto err_ssbi_controller;
 312         }
 313
 314         if (ssbi->controller_type == MSM_SBI_CTRL_PMIC_ARBITER) {
 315                 ssbi->read = ssbi_pa_read_bytes;
 316                 ssbi->write = ssbi_pa_write_bytes;
 317         } else {
 318                 ssbi->read = ssbi_read_bytes;
 319                 ssbi->write = ssbi_write_bytes;
 320         }
 321
 322         spin_lock_init(&ssbi->lock);
 323
 324         ret = of_platform_populate(np, NULL, NULL, &pdev->dev);
 325         if (ret)
 326                 goto err_ssbi_controller;
 327
 328         return 0;
 329
 330 err_ssbi_controller:
 331         platform_set_drvdata(pdev, NULL);
 332         iounmap(ssbi->base);
 333 err_ioremap:
 334 err_get_mem_res:
 335         kfree(ssbi);
 336         return ret;
 337 }
 338
 339 static int ssbi_remove(struct platform_device *pdev)
 340 {
 341         struct ssbi *ssbi = platform_get_drvdata(pdev);
 342
 343         platform_set_drvdata(pdev, NULL);
 344         iounmap(ssbi->base);
 345         kfree(ssbi);
 346         return 0;
 347 }
 348
 349 static struct of_device_id ssbi_match_table[] = {
 350         { .compatible = "qcom,ssbi" },
 351         {}
 352 };
 353
 354 static struct platform_driver ssbi_driver = {
 355         .probe          = ssbi_probe,
 356         .remove         = ssbi_remove,
 357         .driver         = {
 358                 .name   = "ssbi",
 359                 .owner  = THIS_MODULE,
 360                 .of_match_table = ssbi_match_table,
 361         },
 362 };
 363
 364 static int __init ssbi_init(void)
 365 {
 366         return platform_driver_register(&ssbi_driver);
 367 }
 368 module_init(ssbi_init);
 369
 370 static void __exit ssbi_exit(void)
 371 {
 372         platform_driver_unregister(&ssbi_driver);
 373 }
 374 module_exit(ssbi_exit)
 375
 376 MODULE_LICENSE("GPL v2");
 377 MODULE_VERSION("1.0");
 378 MODULE_ALIAS("platform:ssbi");
 379 MODULE_AUTHOR("Dima Zavin <dima@android.com>");