1 /* 2 * BCM2835 master mode driver 3 * 4 * This software is licensed under the terms of the GNU General Public 5 * License version 2, as published by the Free Software Foundation, and 6 * may be copied, distributed, and modified under those terms. 7 * 8 * This program is distributed in the hope that it will be useful, 9 * but WITHOUT ANY WARRANTY; without even the implied warranty of 10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 11 * GNU General Public License for more details. 12 */ 13 14 #include <linux/clk.h> 15 #include <linux/completion.h> 16 #include <linux/err.h> 17 #include <linux/i2c.h> 18 #include <linux/interrupt.h> 19 #include <linux/io.h> 20 #include <linux/module.h> 21 #include <linux/platform_device.h> 22 #include <linux/slab.h> 23 24 #define BCM2835_I2C_C 0x0 25 #define BCM2835_I2C_S 0x4 26 #define BCM2835_I2C_DLEN 0x8 27 #define BCM2835_I2C_A 0xc 28 #define BCM2835_I2C_FIFO 0x10 29 #define BCM2835_I2C_DIV 0x14 30 #define BCM2835_I2C_DEL 0x18 31 #define BCM2835_I2C_CLKT 0x1c 32 33 #define BCM2835_I2C_C_READ BIT(0) 34 #define BCM2835_I2C_C_CLEAR BIT(4) /* bits 4 and 5 both clear */ 35 #define BCM2835_I2C_C_ST BIT(7) 36 #define BCM2835_I2C_C_INTD BIT(8) 37 #define BCM2835_I2C_C_INTT BIT(9) 38 #define BCM2835_I2C_C_INTR BIT(10) 39 #define BCM2835_I2C_C_I2CEN BIT(15) 40 41 #define BCM2835_I2C_S_TA BIT(0) 42 #define BCM2835_I2C_S_DONE BIT(1) 43 #define BCM2835_I2C_S_TXW BIT(2) 44 #define BCM2835_I2C_S_RXR BIT(3) 45 #define BCM2835_I2C_S_TXD BIT(4) 46 #define BCM2835_I2C_S_RXD BIT(5) 47 #define BCM2835_I2C_S_TXE BIT(6) 48 #define BCM2835_I2C_S_RXF BIT(7) 49 #define BCM2835_I2C_S_ERR BIT(8) 50 #define BCM2835_I2C_S_CLKT BIT(9) 51 #define BCM2835_I2C_S_LEN BIT(10) /* Fake bit for SW error reporting */ 52 53 #define BCM2835_I2C_BITMSK_S 0x03FF 54 55 #define BCM2835_I2C_CDIV_MIN 0x0002 56 #define BCM2835_I2C_CDIV_MAX 0xFFFE 57 58 #define BCM2835_I2C_TIMEOUT (msecs_to_jiffies(1000)) 59 60 struct bcm2835_i2c_dev { 61 struct device *dev; 62 void __iomem *regs; 63 struct clk *clk; 64 int irq; 65 struct i2c_adapter adapter; 66 struct completion completion; 67 u32 msg_err; 68 u8 *msg_buf; 69 size_t msg_buf_remaining; 70 }; 71 72 static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev, 73 u32 reg, u32 val) 74 { 75 writel(val, i2c_dev->regs + reg); 76 } 77 78 static inline u32 bcm2835_i2c_readl(struct bcm2835_i2c_dev *i2c_dev, u32 reg) 79 { 80 return readl(i2c_dev->regs + reg); 81 } 82 83 static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) 84 { 85 u32 val; 86 87 while (i2c_dev->msg_buf_remaining) { 88 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); 89 if (!(val & BCM2835_I2C_S_TXD)) 90 break; 91 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_FIFO, 92 *i2c_dev->msg_buf); 93 i2c_dev->msg_buf++; 94 i2c_dev->msg_buf_remaining--; 95 } 96 } 97 98 static void bcm2835_drain_rxfifo(struct bcm2835_i2c_dev *i2c_dev) 99 { 100 u32 val; 101 102 while (i2c_dev->msg_buf_remaining) { 103 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); 104 if (!(val & BCM2835_I2C_S_RXD)) 105 break; 106 *i2c_dev->msg_buf = bcm2835_i2c_readl(i2c_dev, 107 BCM2835_I2C_FIFO); 108 i2c_dev->msg_buf++; 109 i2c_dev->msg_buf_remaining--; 110 } 111 } 112 113 static irqreturn_t bcm2835_i2c_isr(int this_irq, void *data) 114 { 115 struct bcm2835_i2c_dev *i2c_dev = data; 116 u32 val, err; 117 118 val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S); 119 val &= BCM2835_I2C_BITMSK_S; 120 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_S, val); 121 122 err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR); 123 if (err) { 124 i2c_dev->msg_err = err; 125 complete(&i2c_dev->completion); 126 return IRQ_HANDLED; 127 } 128 129 if (val & BCM2835_I2C_S_RXD) { 130 bcm2835_drain_rxfifo(i2c_dev); 131 if (!(val & BCM2835_I2C_S_DONE)) 132 return IRQ_HANDLED; 133 } 134 135 if (val & BCM2835_I2C_S_DONE) { 136 if (i2c_dev->msg_buf_remaining) 137 i2c_dev->msg_err = BCM2835_I2C_S_LEN; 138 else 139 i2c_dev->msg_err = 0; 140 complete(&i2c_dev->completion); 141 return IRQ_HANDLED; 142 } 143 144 if (val & BCM2835_I2C_S_TXD) { 145 bcm2835_fill_txfifo(i2c_dev); 146 return IRQ_HANDLED; 147 } 148 149 return IRQ_NONE; 150 } 151 152 static int bcm2835_i2c_xfer_msg(struct bcm2835_i2c_dev *i2c_dev, 153 struct i2c_msg *msg) 154 { 155 u32 c; 156 unsigned long time_left; 157 158 i2c_dev->msg_buf = msg->buf; 159 i2c_dev->msg_buf_remaining = msg->len; 160 reinit_completion(&i2c_dev->completion); 161 162 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); 163 164 if (msg->flags & I2C_M_RD) { 165 c = BCM2835_I2C_C_READ | BCM2835_I2C_C_INTR; 166 } else { 167 c = BCM2835_I2C_C_INTT; 168 bcm2835_fill_txfifo(i2c_dev); 169 } 170 c |= BCM2835_I2C_C_ST | BCM2835_I2C_C_INTD | BCM2835_I2C_C_I2CEN; 171 172 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr); 173 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len); 174 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c); 175 176 time_left = wait_for_completion_timeout(&i2c_dev->completion, 177 BCM2835_I2C_TIMEOUT); 178 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, BCM2835_I2C_C_CLEAR); 179 if (!time_left) { 180 dev_err(i2c_dev->dev, "i2c transfer timed out\n"); 181 return -ETIMEDOUT; 182 } 183 184 if (likely(!i2c_dev->msg_err)) 185 return 0; 186 187 if ((i2c_dev->msg_err & BCM2835_I2C_S_ERR) && 188 (msg->flags & I2C_M_IGNORE_NAK)) 189 return 0; 190 191 dev_err(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err); 192 193 if (i2c_dev->msg_err & BCM2835_I2C_S_ERR) 194 return -EREMOTEIO; 195 else 196 return -EIO; 197 } 198 199 static int bcm2835_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], 200 int num) 201 { 202 struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); 203 int i; 204 int ret = 0; 205 206 for (i = 0; i < num; i++) { 207 ret = bcm2835_i2c_xfer_msg(i2c_dev, &msgs[i]); 208 if (ret) 209 break; 210 } 211 212 return ret ?: i; 213 } 214 215 static u32 bcm2835_i2c_func(struct i2c_adapter *adap) 216 { 217 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 218 } 219 220 static const struct i2c_algorithm bcm2835_i2c_algo = { 221 .master_xfer = bcm2835_i2c_xfer, 222 .functionality = bcm2835_i2c_func, 223 }; 224 225 static int bcm2835_i2c_probe(struct platform_device *pdev) 226 { 227 struct bcm2835_i2c_dev *i2c_dev; 228 struct resource *mem, *irq; 229 u32 bus_clk_rate, divider; 230 int ret; 231 struct i2c_adapter *adap; 232 233 i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); 234 if (!i2c_dev) 235 return -ENOMEM; 236 platform_set_drvdata(pdev, i2c_dev); 237 i2c_dev->dev = &pdev->dev; 238 init_completion(&i2c_dev->completion); 239 240 mem = platform_get_resource(pdev, IORESOURCE_MEM, 0); 241 i2c_dev->regs = devm_ioremap_resource(&pdev->dev, mem); 242 if (IS_ERR(i2c_dev->regs)) 243 return PTR_ERR(i2c_dev->regs); 244 245 i2c_dev->clk = devm_clk_get(&pdev->dev, NULL); 246 if (IS_ERR(i2c_dev->clk)) { 247 dev_err(&pdev->dev, "Could not get clock\n"); 248 return PTR_ERR(i2c_dev->clk); 249 } 250 251 ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", 252 &bus_clk_rate); 253 if (ret < 0) { 254 dev_warn(&pdev->dev, 255 "Could not read clock-frequency property\n"); 256 bus_clk_rate = 100000; 257 } 258 259 divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate); 260 /* 261 * Per the datasheet, the register is always interpreted as an even 262 * number, by rounding down. In other words, the LSB is ignored. So, 263 * if the LSB is set, increment the divider to avoid any issue. 264 */ 265 if (divider & 1) 266 divider++; 267 if ((divider < BCM2835_I2C_CDIV_MIN) || 268 (divider > BCM2835_I2C_CDIV_MAX)) { 269 dev_err(&pdev->dev, "Invalid clock-frequency\n"); 270 return -ENODEV; 271 } 272 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); 273 274 irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); 275 if (!irq) { 276 dev_err(&pdev->dev, "No IRQ resource\n"); 277 return -ENODEV; 278 } 279 i2c_dev->irq = irq->start; 280 281 ret = request_irq(i2c_dev->irq, bcm2835_i2c_isr, IRQF_SHARED, 282 dev_name(&pdev->dev), i2c_dev); 283 if (ret) { 284 dev_err(&pdev->dev, "Could not request IRQ\n"); 285 return -ENODEV; 286 } 287 288 adap = &i2c_dev->adapter; 289 i2c_set_adapdata(adap, i2c_dev); 290 adap->owner = THIS_MODULE; 291 adap->class = I2C_CLASS_DEPRECATED; 292 strlcpy(adap->name, "bcm2835 I2C adapter", sizeof(adap->name)); 293 adap->algo = &bcm2835_i2c_algo; 294 adap->dev.parent = &pdev->dev; 295 adap->dev.of_node = pdev->dev.of_node; 296 297 bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, 0); 298 299 ret = i2c_add_adapter(adap); 300 if (ret) 301 free_irq(i2c_dev->irq, i2c_dev); 302 303 return ret; 304 } 305 306 static int bcm2835_i2c_remove(struct platform_device *pdev) 307 { 308 struct bcm2835_i2c_dev *i2c_dev = platform_get_drvdata(pdev); 309 310 free_irq(i2c_dev->irq, i2c_dev); 311 i2c_del_adapter(&i2c_dev->adapter); 312 313 return 0; 314 } 315 316 static const struct of_device_id bcm2835_i2c_of_match[] = { 317 { .compatible = "brcm,bcm2835-i2c" }, 318 {}, 319 }; 320 MODULE_DEVICE_TABLE(of, bcm2835_i2c_of_match); 321 322 static struct platform_driver bcm2835_i2c_driver = { 323 .probe = bcm2835_i2c_probe, 324 .remove = bcm2835_i2c_remove, 325 .driver = { 326 .name = "i2c-bcm2835", 327 .of_match_table = bcm2835_i2c_of_match, 328 }, 329 }; 330 module_platform_driver(bcm2835_i2c_driver); 331 332 MODULE_AUTHOR("Stephen Warren <swarren@wwwdotorg.org>"); 333 MODULE_DESCRIPTION("BCM2835 I2C bus adapter"); 334 MODULE_LICENSE("GPL v2"); 335 MODULE_ALIAS("platform:i2c-bcm2835"); 336