1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * drivers/i2c/busses/i2c-ibm_iic.c
5 * Support for the IIC peripheral on IBM PPC 4xx
7 * Copyright (c) 2003, 2004 Zultys Technologies.
8 * Eugene Surovegin <eugene.surovegin@zultys.com> or <ebs@ebshome.net>
10 * Copyright (c) 2008 PIKA Technologies
11 * Sean MacLennan <smaclennan@pikatech.com>
13 * Based on original work by
14 * Ian DaSilva <idasilva@mvista.com>
15 * Armin Kuster <akuster@mvista.com>
16 * Matt Porter <mporter@mvista.com>
18 * Copyright 2000-2003 MontaVista Software Inc.
20 * Original driver version was highly leveraged from i2c-elektor.c
22 * Copyright 1995-97 Simon G. Vogl
23 * 1998-99 Hans Berglund
25 * With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>
26 * and even Frodo Looijaard <frodol@dds.nl>
29 #include <linux/module.h>
30 #include <linux/kernel.h>
31 #include <linux/ioport.h>
32 #include <linux/delay.h>
33 #include <linux/slab.h>
34 #include <linux/interrupt.h>
35 #include <linux/sched/signal.h>
39 #include <linux/i2c.h>
41 #include <linux/of_address.h>
42 #include <linux/of_irq.h>
43 #include <linux/platform_device.h>
45 #include "i2c-ibm_iic.h"
47 #define DRIVER_VERSION "2.2"
49 MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION);
50 MODULE_LICENSE("GPL");
52 static bool iic_force_poll;
53 module_param(iic_force_poll, bool, 0);
54 MODULE_PARM_DESC(iic_force_poll, "Force polling mode");
56 static bool iic_force_fast;
57 module_param(iic_force_fast, bool, 0);
58 MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)");
71 # define DBG(f,x...) printk(KERN_DEBUG "ibm-iic" f, ##x)
73 # define DBG(f,x...) ((void)0)
76 # define DBG2(f,x...) DBG(f, ##x)
78 # define DBG2(f,x...) ((void)0)
81 static void dump_iic_regs(const char* header, struct ibm_iic_private* dev)
83 volatile struct iic_regs __iomem *iic = dev->vaddr;
84 printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header);
86 " cntl = 0x%02x, mdcntl = 0x%02x\n"
87 " sts = 0x%02x, extsts = 0x%02x\n"
88 " clkdiv = 0x%02x, xfrcnt = 0x%02x\n"
89 " xtcntlss = 0x%02x, directcntl = 0x%02x\n",
90 in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts),
91 in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt),
92 in_8(&iic->xtcntlss), in_8(&iic->directcntl));
94 # define DUMP_REGS(h,dev) dump_iic_regs((h),(dev))
96 # define DUMP_REGS(h,dev) ((void)0)
99 /* Bus timings (in ns) for bit-banging */
100 static struct ibm_iic_timings {
107 /* Standard mode (100 KHz) */
115 /* Fast mode (400 KHz) */
124 /* Enable/disable interrupt generation */
125 static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable)
127 out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0);
131 * Initialize IIC interface.
133 static void iic_dev_init(struct ibm_iic_private* dev)
135 volatile struct iic_regs __iomem *iic = dev->vaddr;
137 DBG("%d: init\n", dev->idx);
139 /* Clear master address */
140 out_8(&iic->lmadr, 0);
141 out_8(&iic->hmadr, 0);
143 /* Clear slave address */
144 out_8(&iic->lsadr, 0);
145 out_8(&iic->hsadr, 0);
147 /* Clear status & extended status */
148 out_8(&iic->sts, STS_SCMP | STS_IRQA);
149 out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA
150 | EXTSTS_ICT | EXTSTS_XFRA);
152 /* Set clock divider */
153 out_8(&iic->clkdiv, dev->clckdiv);
155 /* Clear transfer count */
156 out_8(&iic->xfrcnt, 0);
158 /* Clear extended control and status */
159 out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC
162 /* Clear control register */
163 out_8(&iic->cntl, 0);
165 /* Enable interrupts if possible */
166 iic_interrupt_mode(dev, dev->irq >= 0);
168 /* Set mode control */
169 out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS
170 | (dev->fast_mode ? MDCNTL_FSM : 0));
172 DUMP_REGS("iic_init", dev);
176 * Reset IIC interface
178 static void iic_dev_reset(struct ibm_iic_private* dev)
180 volatile struct iic_regs __iomem *iic = dev->vaddr;
184 DBG("%d: soft reset\n", dev->idx);
185 DUMP_REGS("reset", dev);
187 /* Place chip in the reset state */
188 out_8(&iic->xtcntlss, XTCNTLSS_SRST);
190 /* Check if bus is free */
191 dc = in_8(&iic->directcntl);
192 if (!DIRCTNL_FREE(dc)){
193 DBG("%d: trying to regain bus control\n", dev->idx);
195 /* Try to set bus free state */
196 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
198 /* Wait until we regain bus control */
199 for (i = 0; i < 100; ++i){
200 dc = in_8(&iic->directcntl);
201 if (DIRCTNL_FREE(dc))
204 /* Toggle SCL line */
206 out_8(&iic->directcntl, dc);
209 out_8(&iic->directcntl, dc);
217 out_8(&iic->xtcntlss, 0);
219 /* Reinitialize interface */
224 * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register.
227 /* Wait for SCL and/or SDA to be high */
228 static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask)
230 unsigned long x = jiffies + HZ / 28 + 2;
231 while ((in_8(&iic->directcntl) & mask) != mask){
232 if (unlikely(time_after(jiffies, x)))
239 static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p)
241 volatile struct iic_regs __iomem *iic = dev->vaddr;
242 const struct ibm_iic_timings *t = &timings[dev->fast_mode ? 1 : 0];
246 /* Only 7-bit addresses are supported */
247 if (unlikely(p->flags & I2C_M_TEN)){
248 DBG("%d: smbus_quick - 10 bit addresses are not supported\n",
253 DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr);
255 /* Reset IIC interface */
256 out_8(&iic->xtcntlss, XTCNTLSS_SRST);
258 /* Wait for bus to become free */
259 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
260 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC)))
265 out_8(&iic->directcntl, DIRCNTL_SCC);
270 v = i2c_8bit_addr_from_msg(p);
271 for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){
272 out_8(&iic->directcntl, sda);
274 sda = (v & mask) ? DIRCNTL_SDAC : 0;
275 out_8(&iic->directcntl, sda);
278 out_8(&iic->directcntl, DIRCNTL_SCC | sda);
279 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
285 out_8(&iic->directcntl, sda);
287 out_8(&iic->directcntl, DIRCNTL_SDAC);
289 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
290 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
292 res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1;
296 out_8(&iic->directcntl, 0);
298 out_8(&iic->directcntl, DIRCNTL_SCC);
299 if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC)))
302 out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC);
306 DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK");
309 out_8(&iic->xtcntlss, 0);
311 /* Reinitialize interface */
316 DBG("%d: smbus_quick - bus is stuck\n", dev->idx);
322 * IIC interrupt handler
324 static irqreturn_t iic_handler(int irq, void *dev_id)
326 struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id;
327 volatile struct iic_regs __iomem *iic = dev->vaddr;
329 DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n",
330 dev->idx, in_8(&iic->sts), in_8(&iic->extsts));
332 /* Acknowledge IRQ and wakeup iic_wait_for_tc */
333 out_8(&iic->sts, STS_IRQA | STS_SCMP);
334 wake_up_interruptible(&dev->wq);
340 * Get master transfer result and clear errors if any.
341 * Returns the number of actually transferred bytes or error (<0)
343 static int iic_xfer_result(struct ibm_iic_private* dev)
345 volatile struct iic_regs __iomem *iic = dev->vaddr;
347 if (unlikely(in_8(&iic->sts) & STS_ERR)){
348 DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx,
351 /* Clear errors and possible pending IRQs */
352 out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD |
353 EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA);
355 /* Flush master data buffer */
356 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
359 * If error happened during combined xfer
360 * IIC interface is usually stuck in some strange
361 * state, the only way out - soft reset.
363 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
364 DBG("%d: bus is stuck, resetting\n", dev->idx);
370 return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK;
374 * Try to abort active transfer.
376 static void iic_abort_xfer(struct ibm_iic_private* dev)
378 volatile struct iic_regs __iomem *iic = dev->vaddr;
381 DBG("%d: iic_abort_xfer\n", dev->idx);
383 out_8(&iic->cntl, CNTL_HMT);
386 * Wait for the abort command to complete.
387 * It's not worth to be optimized, just poll (timeout >= 1 tick)
390 while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
391 if (time_after(jiffies, x)){
392 DBG("%d: abort timeout, resetting...\n", dev->idx);
399 /* Just to clear errors */
400 iic_xfer_result(dev);
404 * Wait for master transfer to complete.
405 * It puts current process to sleep until we get interrupt or timeout expires.
406 * Returns the number of transferred bytes or error (<0)
408 static int iic_wait_for_tc(struct ibm_iic_private* dev){
410 volatile struct iic_regs __iomem *iic = dev->vaddr;
415 ret = wait_event_interruptible_timeout(dev->wq,
416 !(in_8(&iic->sts) & STS_PT), dev->adap.timeout);
418 if (unlikely(ret < 0))
419 DBG("%d: wait interrupted\n", dev->idx);
420 else if (unlikely(in_8(&iic->sts) & STS_PT)){
421 DBG("%d: wait timeout\n", dev->idx);
427 unsigned long x = jiffies + dev->adap.timeout;
429 while (in_8(&iic->sts) & STS_PT){
430 if (unlikely(time_after(jiffies, x))){
431 DBG("%d: poll timeout\n", dev->idx);
436 if (signal_pending(current)){
437 DBG("%d: poll interrupted\n", dev->idx);
445 if (unlikely(ret < 0))
448 ret = iic_xfer_result(dev);
450 DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret);
456 * Low level master transfer routine
458 static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm,
461 volatile struct iic_regs __iomem *iic = dev->vaddr;
463 int i, j, loops, ret = 0;
466 u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT;
467 if (pm->flags & I2C_M_RD)
470 loops = (len + 3) / 4;
471 for (i = 0; i < loops; ++i, len -= 4){
472 int count = len > 4 ? 4 : len;
473 u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT);
475 if (!(cntl & CNTL_RW))
476 for (j = 0; j < count; ++j)
477 out_8((void __iomem *)&iic->mdbuf, *buf++);
481 else if (combined_xfer)
484 DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd);
487 out_8(&iic->cntl, cmd);
489 /* Wait for completion */
490 ret = iic_wait_for_tc(dev);
492 if (unlikely(ret < 0))
494 else if (unlikely(ret != count)){
495 DBG("%d: xfer_bytes, requested %d, transferred %d\n",
496 dev->idx, count, ret);
498 /* If it's not a last part of xfer, abort it */
499 if (combined_xfer || (i < loops - 1))
507 for (j = 0; j < count; ++j)
508 *buf++ = in_8((void __iomem *)&iic->mdbuf);
511 return ret > 0 ? 0 : ret;
515 * Set target slave address for master transfer
517 static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg)
519 volatile struct iic_regs __iomem *iic = dev->vaddr;
520 u16 addr = msg->addr;
522 DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx,
523 addr, msg->flags & I2C_M_TEN ? 10 : 7);
525 if (msg->flags & I2C_M_TEN){
526 out_8(&iic->cntl, CNTL_AMD);
527 out_8(&iic->lmadr, addr);
528 out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06));
531 out_8(&iic->cntl, 0);
532 out_8(&iic->lmadr, addr << 1);
536 static inline int iic_invalid_address(const struct i2c_msg* p)
538 return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f));
541 static inline int iic_address_neq(const struct i2c_msg* p1,
542 const struct i2c_msg* p2)
544 return (p1->addr != p2->addr)
545 || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN));
549 * Generic master transfer entrypoint.
550 * Returns the number of processed messages or error (<0)
552 static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
554 struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap));
555 volatile struct iic_regs __iomem *iic = dev->vaddr;
558 DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num);
560 /* Check the sanity of the passed messages.
561 * Uhh, generic i2c layer is more suitable place for such code...
563 if (unlikely(iic_invalid_address(&msgs[0]))){
564 DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx,
565 msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7);
568 for (i = 0; i < num; ++i){
569 if (unlikely(msgs[i].len <= 0)){
570 if (num == 1 && !msgs[0].len){
571 /* Special case for I2C_SMBUS_QUICK emulation.
572 * IBM IIC doesn't support 0-length transactions
573 * so we have to emulate them using bit-banging.
575 return iic_smbus_quick(dev, &msgs[0]);
577 DBG("%d: invalid len %d in msg[%d]\n", dev->idx,
581 if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){
582 DBG("%d: invalid addr in msg[%d]\n", dev->idx, i);
587 /* Check bus state */
588 if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){
589 DBG("%d: iic_xfer, bus is not free\n", dev->idx);
591 /* Usually it means something serious has happened.
592 * We *cannot* have unfinished previous transfer
593 * so it doesn't make any sense to try to stop it.
594 * Probably we were not able to recover from the
596 * The only *reasonable* thing I can think of here
597 * is soft reset. --ebs
601 if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){
602 DBG("%d: iic_xfer, bus is still not free\n", dev->idx);
607 /* Flush master data buffer (just in case) */
608 out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB);
611 /* Load slave address */
612 iic_address(dev, &msgs[0]);
614 /* Do real transfer */
615 for (i = 0; i < num && !ret; ++i)
616 ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1);
618 return ret < 0 ? ret : num;
621 static u32 iic_func(struct i2c_adapter *adap)
623 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
626 static const struct i2c_algorithm iic_algo = {
627 .master_xfer = iic_xfer,
628 .functionality = iic_func
632 * Calculates IICx_CLCKDIV value for a specific OPB clock frequency
634 static inline u8 iic_clckdiv(unsigned int opb)
636 /* Compatibility kludge, should go away after all cards
637 * are fixed to fill correct value for opbfreq.
638 * Previous driver version used hardcoded divider value 4,
639 * it corresponds to OPB frequency from the range (40, 50] MHz
642 printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq,"
643 " fix your board specific setup\n");
650 if (opb < 20 || opb > 150){
651 printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n",
653 opb = opb < 20 ? 20 : 150;
655 return (u8)((opb + 9) / 10 - 1);
658 static int iic_request_irq(struct platform_device *ofdev,
659 struct ibm_iic_private *dev)
661 struct device_node *np = ofdev->dev.of_node;
667 irq = irq_of_parse_and_map(np, 0);
669 dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n");
673 /* Disable interrupts until we finish initialization, assumes
674 * level-sensitive IRQ setup...
676 iic_interrupt_mode(dev, 0);
677 if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) {
678 dev_err(&ofdev->dev, "request_irq %d failed\n", irq);
679 /* Fallback to the polling mode */
687 * Register single IIC interface
689 static int iic_probe(struct platform_device *ofdev)
691 struct device_node *np = ofdev->dev.of_node;
692 struct ibm_iic_private *dev;
693 struct i2c_adapter *adap;
697 dev = kzalloc(sizeof(*dev), GFP_KERNEL);
701 platform_set_drvdata(ofdev, dev);
703 dev->vaddr = of_iomap(np, 0);
704 if (dev->vaddr == NULL) {
705 dev_err(&ofdev->dev, "failed to iomap device\n");
710 init_waitqueue_head(&dev->wq);
712 dev->irq = iic_request_irq(ofdev, dev);
714 dev_warn(&ofdev->dev, "using polling mode\n");
716 /* Board specific settings */
717 if (iic_force_fast || of_get_property(np, "fast-mode", NULL))
720 freq = of_get_property(np, "clock-frequency", NULL);
722 freq = of_get_property(np->parent, "clock-frequency", NULL);
724 dev_err(&ofdev->dev, "Unable to get bus frequency\n");
730 dev->clckdiv = iic_clckdiv(*freq);
731 dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv);
733 /* Initialize IIC interface */
736 /* Register it with i2c layer */
738 adap->dev.parent = &ofdev->dev;
739 adap->dev.of_node = of_node_get(np);
740 strscpy(adap->name, "IBM IIC", sizeof(adap->name));
741 i2c_set_adapdata(adap, dev);
742 adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
743 adap->algo = &iic_algo;
746 ret = i2c_add_adapter(adap);
750 dev_info(&ofdev->dev, "using %s mode\n",
751 dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)");
757 iic_interrupt_mode(dev, 0);
758 free_irq(dev->irq, dev);
769 * Cleanup initialized IIC interface
771 static void iic_remove(struct platform_device *ofdev)
773 struct ibm_iic_private *dev = platform_get_drvdata(ofdev);
775 i2c_del_adapter(&dev->adap);
778 iic_interrupt_mode(dev, 0);
779 free_irq(dev->irq, dev);
786 static const struct of_device_id ibm_iic_match[] = {
787 { .compatible = "ibm,iic", },
790 MODULE_DEVICE_TABLE(of, ibm_iic_match);
792 static struct platform_driver ibm_iic_driver = {
795 .of_match_table = ibm_iic_match,
798 .remove_new = iic_remove,
801 module_platform_driver(ibm_iic_driver);