1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * i2c-au1550.c: SMBus (i2c) adapter for Alchemy PSC interface 4 * Copyright (C) 2004 Embedded Edge, LLC <dan@embeddededge.com> 5 * 6 * 2.6 port by Matt Porter <mporter@kernel.crashing.org> 7 * 8 * The documentation describes this as an SMBus controller, but it doesn't 9 * understand any of the SMBus protocol in hardware. It's really an I2C 10 * controller that could emulate most of the SMBus in software. 11 * 12 * This is just a skeleton adapter to use with the Au1550 PSC 13 * algorithm. It was developed for the Pb1550, but will work with 14 * any Au1550 board that has a similar PSC configuration. 15 */ 16 17 #include <linux/delay.h> 18 #include <linux/kernel.h> 19 #include <linux/module.h> 20 #include <linux/platform_device.h> 21 #include <linux/errno.h> 22 #include <linux/i2c.h> 23 #include <linux/slab.h> 24 25 #include <asm/mach-au1x00/au1000.h> 26 #include <asm/mach-au1x00/au1xxx_psc.h> 27 28 #define PSC_SEL 0x00 29 #define PSC_CTRL 0x04 30 #define PSC_SMBCFG 0x08 31 #define PSC_SMBMSK 0x0C 32 #define PSC_SMBPCR 0x10 33 #define PSC_SMBSTAT 0x14 34 #define PSC_SMBEVNT 0x18 35 #define PSC_SMBTXRX 0x1C 36 #define PSC_SMBTMR 0x20 37 38 struct i2c_au1550_data { 39 void __iomem *psc_base; 40 int xfer_timeout; 41 struct i2c_adapter adap; 42 }; 43 44 static inline void WR(struct i2c_au1550_data *a, int r, unsigned long v) 45 { 46 __raw_writel(v, a->psc_base + r); 47 wmb(); 48 } 49 50 static inline unsigned long RD(struct i2c_au1550_data *a, int r) 51 { 52 return __raw_readl(a->psc_base + r); 53 } 54 55 static int wait_xfer_done(struct i2c_au1550_data *adap) 56 { 57 int i; 58 59 /* Wait for Tx Buffer Empty */ 60 for (i = 0; i < adap->xfer_timeout; i++) { 61 if (RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_TE) 62 return 0; 63 64 udelay(1); 65 } 66 67 return -ETIMEDOUT; 68 } 69 70 static int wait_ack(struct i2c_au1550_data *adap) 71 { 72 unsigned long stat; 73 74 if (wait_xfer_done(adap)) 75 return -ETIMEDOUT; 76 77 stat = RD(adap, PSC_SMBEVNT); 78 if ((stat & (PSC_SMBEVNT_DN | PSC_SMBEVNT_AN | PSC_SMBEVNT_AL)) != 0) 79 return -ETIMEDOUT; 80 81 return 0; 82 } 83 84 static int wait_master_done(struct i2c_au1550_data *adap) 85 { 86 int i; 87 88 /* Wait for Master Done. */ 89 for (i = 0; i < 2 * adap->xfer_timeout; i++) { 90 if ((RD(adap, PSC_SMBEVNT) & PSC_SMBEVNT_MD) != 0) 91 return 0; 92 udelay(1); 93 } 94 95 return -ETIMEDOUT; 96 } 97 98 static int 99 do_address(struct i2c_au1550_data *adap, unsigned int addr, int rd, int q) 100 { 101 unsigned long stat; 102 103 /* Reset the FIFOs, clear events. */ 104 stat = RD(adap, PSC_SMBSTAT); 105 WR(adap, PSC_SMBEVNT, PSC_SMBEVNT_ALLCLR); 106 107 if (!(stat & PSC_SMBSTAT_TE) || !(stat & PSC_SMBSTAT_RE)) { 108 WR(adap, PSC_SMBPCR, PSC_SMBPCR_DC); 109 while ((RD(adap, PSC_SMBPCR) & PSC_SMBPCR_DC) != 0) 110 cpu_relax(); 111 udelay(50); 112 } 113 114 /* Write out the i2c chip address and specify operation */ 115 addr <<= 1; 116 if (rd) 117 addr |= 1; 118 119 /* zero-byte xfers stop immediately */ 120 if (q) 121 addr |= PSC_SMBTXRX_STP; 122 123 /* Put byte into fifo, start up master. */ 124 WR(adap, PSC_SMBTXRX, addr); 125 WR(adap, PSC_SMBPCR, PSC_SMBPCR_MS); 126 if (wait_ack(adap)) 127 return -EIO; 128 return (q) ? wait_master_done(adap) : 0; 129 } 130 131 static int wait_for_rx_byte(struct i2c_au1550_data *adap, unsigned char *out) 132 { 133 int j; 134 135 if (wait_xfer_done(adap)) 136 return -EIO; 137 138 j = adap->xfer_timeout * 100; 139 do { 140 j--; 141 if (j <= 0) 142 return -EIO; 143 144 if ((RD(adap, PSC_SMBSTAT) & PSC_SMBSTAT_RE) == 0) 145 j = 0; 146 else 147 udelay(1); 148 } while (j > 0); 149 150 *out = RD(adap, PSC_SMBTXRX); 151 152 return 0; 153 } 154 155 static int i2c_read(struct i2c_au1550_data *adap, unsigned char *buf, 156 unsigned int len) 157 { 158 int i; 159 160 if (len == 0) 161 return 0; 162 163 /* A read is performed by stuffing the transmit fifo with 164 * zero bytes for timing, waiting for bytes to appear in the 165 * receive fifo, then reading the bytes. 166 */ 167 i = 0; 168 while (i < (len - 1)) { 169 WR(adap, PSC_SMBTXRX, 0); 170 if (wait_for_rx_byte(adap, &buf[i])) 171 return -EIO; 172 173 i++; 174 } 175 176 /* The last byte has to indicate transfer done. */ 177 WR(adap, PSC_SMBTXRX, PSC_SMBTXRX_STP); 178 if (wait_master_done(adap)) 179 return -EIO; 180 181 buf[i] = (unsigned char)(RD(adap, PSC_SMBTXRX) & 0xff); 182 return 0; 183 } 184 185 static int i2c_write(struct i2c_au1550_data *adap, unsigned char *buf, 186 unsigned int len) 187 { 188 int i; 189 unsigned long data; 190 191 if (len == 0) 192 return 0; 193 194 i = 0; 195 while (i < (len-1)) { 196 data = buf[i]; 197 WR(adap, PSC_SMBTXRX, data); 198 if (wait_ack(adap)) 199 return -EIO; 200 i++; 201 } 202 203 /* The last byte has to indicate transfer done. */ 204 data = buf[i]; 205 data |= PSC_SMBTXRX_STP; 206 WR(adap, PSC_SMBTXRX, data); 207 if (wait_master_done(adap)) 208 return -EIO; 209 return 0; 210 } 211 212 static int 213 au1550_xfer(struct i2c_adapter *i2c_adap, struct i2c_msg *msgs, int num) 214 { 215 struct i2c_au1550_data *adap = i2c_adap->algo_data; 216 struct i2c_msg *p; 217 int i, err = 0; 218 219 WR(adap, PSC_CTRL, PSC_CTRL_ENABLE); 220 221 for (i = 0; !err && i < num; i++) { 222 p = &msgs[i]; 223 err = do_address(adap, p->addr, p->flags & I2C_M_RD, 224 (p->len == 0)); 225 if (err || !p->len) 226 continue; 227 if (p->flags & I2C_M_RD) 228 err = i2c_read(adap, p->buf, p->len); 229 else 230 err = i2c_write(adap, p->buf, p->len); 231 } 232 233 /* Return the number of messages processed, or the error code. 234 */ 235 if (err == 0) 236 err = num; 237 238 WR(adap, PSC_CTRL, PSC_CTRL_SUSPEND); 239 240 return err; 241 } 242 243 static u32 au1550_func(struct i2c_adapter *adap) 244 { 245 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; 246 } 247 248 static const struct i2c_algorithm au1550_algo = { 249 .master_xfer = au1550_xfer, 250 .functionality = au1550_func, 251 }; 252 253 static void i2c_au1550_setup(struct i2c_au1550_data *priv) 254 { 255 unsigned long cfg; 256 257 WR(priv, PSC_CTRL, PSC_CTRL_DISABLE); 258 WR(priv, PSC_SEL, PSC_SEL_PS_SMBUSMODE); 259 WR(priv, PSC_SMBCFG, 0); 260 WR(priv, PSC_CTRL, PSC_CTRL_ENABLE); 261 while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0) 262 cpu_relax(); 263 264 cfg = PSC_SMBCFG_RT_FIFO8 | PSC_SMBCFG_TT_FIFO8 | PSC_SMBCFG_DD_DISABLE; 265 WR(priv, PSC_SMBCFG, cfg); 266 267 /* Divide by 8 to get a 6.25 MHz clock. The later protocol 268 * timings are based on this clock. 269 */ 270 cfg |= PSC_SMBCFG_SET_DIV(PSC_SMBCFG_DIV8); 271 WR(priv, PSC_SMBCFG, cfg); 272 WR(priv, PSC_SMBMSK, PSC_SMBMSK_ALLMASK); 273 274 /* Set the protocol timer values. See Table 71 in the 275 * Au1550 Data Book for standard timing values. 276 */ 277 WR(priv, PSC_SMBTMR, PSC_SMBTMR_SET_TH(0) | PSC_SMBTMR_SET_PS(20) | \ 278 PSC_SMBTMR_SET_PU(20) | PSC_SMBTMR_SET_SH(20) | \ 279 PSC_SMBTMR_SET_SU(20) | PSC_SMBTMR_SET_CL(20) | \ 280 PSC_SMBTMR_SET_CH(20)); 281 282 cfg |= PSC_SMBCFG_DE_ENABLE; 283 WR(priv, PSC_SMBCFG, cfg); 284 while ((RD(priv, PSC_SMBSTAT) & PSC_SMBSTAT_SR) == 0) 285 cpu_relax(); 286 287 WR(priv, PSC_CTRL, PSC_CTRL_SUSPEND); 288 } 289 290 static void i2c_au1550_disable(struct i2c_au1550_data *priv) 291 { 292 WR(priv, PSC_SMBCFG, 0); 293 WR(priv, PSC_CTRL, PSC_CTRL_DISABLE); 294 } 295 296 /* 297 * registering functions to load algorithms at runtime 298 * Prior to calling us, the 50MHz clock frequency and routing 299 * must have been set up for the PSC indicated by the adapter. 300 */ 301 static int 302 i2c_au1550_probe(struct platform_device *pdev) 303 { 304 struct i2c_au1550_data *priv; 305 int ret; 306 307 priv = devm_kzalloc(&pdev->dev, sizeof(struct i2c_au1550_data), 308 GFP_KERNEL); 309 if (!priv) 310 return -ENOMEM; 311 312 priv->psc_base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); 313 if (IS_ERR(priv->psc_base)) 314 return PTR_ERR(priv->psc_base); 315 316 priv->xfer_timeout = 200; 317 318 priv->adap.nr = pdev->id; 319 priv->adap.algo = &au1550_algo; 320 priv->adap.algo_data = priv; 321 priv->adap.dev.parent = &pdev->dev; 322 strscpy(priv->adap.name, "Au1xxx PSC I2C", sizeof(priv->adap.name)); 323 324 /* Now, set up the PSC for SMBus PIO mode. */ 325 i2c_au1550_setup(priv); 326 327 ret = i2c_add_numbered_adapter(&priv->adap); 328 if (ret) { 329 i2c_au1550_disable(priv); 330 return ret; 331 } 332 333 platform_set_drvdata(pdev, priv); 334 return 0; 335 } 336 337 static void i2c_au1550_remove(struct platform_device *pdev) 338 { 339 struct i2c_au1550_data *priv = platform_get_drvdata(pdev); 340 341 i2c_del_adapter(&priv->adap); 342 i2c_au1550_disable(priv); 343 } 344 345 static int i2c_au1550_suspend(struct device *dev) 346 { 347 struct i2c_au1550_data *priv = dev_get_drvdata(dev); 348 349 i2c_au1550_disable(priv); 350 351 return 0; 352 } 353 354 static int i2c_au1550_resume(struct device *dev) 355 { 356 struct i2c_au1550_data *priv = dev_get_drvdata(dev); 357 358 i2c_au1550_setup(priv); 359 360 return 0; 361 } 362 363 static DEFINE_SIMPLE_DEV_PM_OPS(i2c_au1550_pmops, 364 i2c_au1550_suspend, i2c_au1550_resume); 365 366 static struct platform_driver au1xpsc_smbus_driver = { 367 .driver = { 368 .name = "au1xpsc_smbus", 369 .pm = pm_sleep_ptr(&i2c_au1550_pmops), 370 }, 371 .probe = i2c_au1550_probe, 372 .remove_new = i2c_au1550_remove, 373 }; 374 375 module_platform_driver(au1xpsc_smbus_driver); 376 377 MODULE_AUTHOR("Dan Malek, Embedded Edge, LLC."); 378 MODULE_DESCRIPTION("SMBus adapter Alchemy pb1550"); 379 MODULE_LICENSE("GPL"); 380 MODULE_ALIAS("platform:au1xpsc_smbus"); 381