/* * drivers/i2c/busses/i2c-ibm_iic.c * * Support for the IIC peripheral on IBM PPC 4xx * * Copyright (c) 2003, 2004 Zultys Technologies. * Eugene Surovegin or * * Copyright (c) 2008 PIKA Technologies * Sean MacLennan * * Based on original work by * Ian DaSilva * Armin Kuster * Matt Porter * * Copyright 2000-2003 MontaVista Software Inc. * * Original driver version was highly leveraged from i2c-elektor.c * * Copyright 1995-97 Simon G. Vogl * 1998-99 Hans Berglund * * With some changes from Kyösti Mälkki * and even Frodo Looijaard * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; either version 2 of the License, or (at your * option) any later version. * */ #include #include #include #include #include #include #include #include #include #include #include #include #include "i2c-ibm_iic.h" #define DRIVER_VERSION "2.2" MODULE_DESCRIPTION("IBM IIC driver v" DRIVER_VERSION); MODULE_LICENSE("GPL"); static bool iic_force_poll; module_param(iic_force_poll, bool, 0); MODULE_PARM_DESC(iic_force_poll, "Force polling mode"); static bool iic_force_fast; module_param(iic_force_fast, bool, 0); MODULE_PARM_DESC(iic_force_fast, "Force fast mode (400 kHz)"); #define DBG_LEVEL 0 #ifdef DBG #undef DBG #endif #ifdef DBG2 #undef DBG2 #endif #if DBG_LEVEL > 0 # define DBG(f,x...) printk(KERN_DEBUG "ibm-iic" f, ##x) #else # define DBG(f,x...) ((void)0) #endif #if DBG_LEVEL > 1 # define DBG2(f,x...) DBG(f, ##x) #else # define DBG2(f,x...) ((void)0) #endif #if DBG_LEVEL > 2 static void dump_iic_regs(const char* header, struct ibm_iic_private* dev) { volatile struct iic_regs __iomem *iic = dev->vaddr; printk(KERN_DEBUG "ibm-iic%d: %s\n", dev->idx, header); printk(KERN_DEBUG " cntl = 0x%02x, mdcntl = 0x%02x\n" " sts = 0x%02x, extsts = 0x%02x\n" " clkdiv = 0x%02x, xfrcnt = 0x%02x\n" " xtcntlss = 0x%02x, directcntl = 0x%02x\n", in_8(&iic->cntl), in_8(&iic->mdcntl), in_8(&iic->sts), in_8(&iic->extsts), in_8(&iic->clkdiv), in_8(&iic->xfrcnt), in_8(&iic->xtcntlss), in_8(&iic->directcntl)); } # define DUMP_REGS(h,dev) dump_iic_regs((h),(dev)) #else # define DUMP_REGS(h,dev) ((void)0) #endif /* Bus timings (in ns) for bit-banging */ static struct i2c_timings { unsigned int hd_sta; unsigned int su_sto; unsigned int low; unsigned int high; unsigned int buf; } timings [] = { /* Standard mode (100 KHz) */ { .hd_sta = 4000, .su_sto = 4000, .low = 4700, .high = 4000, .buf = 4700, }, /* Fast mode (400 KHz) */ { .hd_sta = 600, .su_sto = 600, .low = 1300, .high = 600, .buf = 1300, }}; /* Enable/disable interrupt generation */ static inline void iic_interrupt_mode(struct ibm_iic_private* dev, int enable) { out_8(&dev->vaddr->intmsk, enable ? INTRMSK_EIMTC : 0); } /* * Initialize IIC interface. */ static void iic_dev_init(struct ibm_iic_private* dev) { volatile struct iic_regs __iomem *iic = dev->vaddr; DBG("%d: init\n", dev->idx); /* Clear master address */ out_8(&iic->lmadr, 0); out_8(&iic->hmadr, 0); /* Clear slave address */ out_8(&iic->lsadr, 0); out_8(&iic->hsadr, 0); /* Clear status & extended status */ out_8(&iic->sts, STS_SCMP | STS_IRQA); out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA); /* Set clock divider */ out_8(&iic->clkdiv, dev->clckdiv); /* Clear transfer count */ out_8(&iic->xfrcnt, 0); /* Clear extended control and status */ out_8(&iic->xtcntlss, XTCNTLSS_SRC | XTCNTLSS_SRS | XTCNTLSS_SWC | XTCNTLSS_SWS); /* Clear control register */ out_8(&iic->cntl, 0); /* Enable interrupts if possible */ iic_interrupt_mode(dev, dev->irq >= 0); /* Set mode control */ out_8(&iic->mdcntl, MDCNTL_FMDB | MDCNTL_EINT | MDCNTL_EUBS | (dev->fast_mode ? MDCNTL_FSM : 0)); DUMP_REGS("iic_init", dev); } /* * Reset IIC interface */ static void iic_dev_reset(struct ibm_iic_private* dev) { volatile struct iic_regs __iomem *iic = dev->vaddr; int i; u8 dc; DBG("%d: soft reset\n", dev->idx); DUMP_REGS("reset", dev); /* Place chip in the reset state */ out_8(&iic->xtcntlss, XTCNTLSS_SRST); /* Check if bus is free */ dc = in_8(&iic->directcntl); if (!DIRCTNL_FREE(dc)){ DBG("%d: trying to regain bus control\n", dev->idx); /* Try to set bus free state */ out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC); /* Wait until we regain bus control */ for (i = 0; i < 100; ++i){ dc = in_8(&iic->directcntl); if (DIRCTNL_FREE(dc)) break; /* Toggle SCL line */ dc ^= DIRCNTL_SCC; out_8(&iic->directcntl, dc); udelay(10); dc ^= DIRCNTL_SCC; out_8(&iic->directcntl, dc); /* be nice */ cond_resched(); } } /* Remove reset */ out_8(&iic->xtcntlss, 0); /* Reinitialize interface */ iic_dev_init(dev); } /* * Do 0-length transaction using bit-banging through IIC_DIRECTCNTL register. */ /* Wait for SCL and/or SDA to be high */ static int iic_dc_wait(volatile struct iic_regs __iomem *iic, u8 mask) { unsigned long x = jiffies + HZ / 28 + 2; while ((in_8(&iic->directcntl) & mask) != mask){ if (unlikely(time_after(jiffies, x))) return -1; cond_resched(); } return 0; } static int iic_smbus_quick(struct ibm_iic_private* dev, const struct i2c_msg* p) { volatile struct iic_regs __iomem *iic = dev->vaddr; const struct i2c_timings* t = &timings[dev->fast_mode ? 1 : 0]; u8 mask, v, sda; int i, res; /* Only 7-bit addresses are supported */ if (unlikely(p->flags & I2C_M_TEN)){ DBG("%d: smbus_quick - 10 bit addresses are not supported\n", dev->idx); return -EINVAL; } DBG("%d: smbus_quick(0x%02x)\n", dev->idx, p->addr); /* Reset IIC interface */ out_8(&iic->xtcntlss, XTCNTLSS_SRST); /* Wait for bus to become free */ out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC); if (unlikely(iic_dc_wait(iic, DIRCNTL_MSDA | DIRCNTL_MSC))) goto err; ndelay(t->buf); /* START */ out_8(&iic->directcntl, DIRCNTL_SCC); sda = 0; ndelay(t->hd_sta); /* Send address */ v = (u8)((p->addr << 1) | ((p->flags & I2C_M_RD) ? 1 : 0)); for (i = 0, mask = 0x80; i < 8; ++i, mask >>= 1){ out_8(&iic->directcntl, sda); ndelay(t->low / 2); sda = (v & mask) ? DIRCNTL_SDAC : 0; out_8(&iic->directcntl, sda); ndelay(t->low / 2); out_8(&iic->directcntl, DIRCNTL_SCC | sda); if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC))) goto err; ndelay(t->high); } /* ACK */ out_8(&iic->directcntl, sda); ndelay(t->low / 2); out_8(&iic->directcntl, DIRCNTL_SDAC); ndelay(t->low / 2); out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC); if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC))) goto err; res = (in_8(&iic->directcntl) & DIRCNTL_MSDA) ? -EREMOTEIO : 1; ndelay(t->high); /* STOP */ out_8(&iic->directcntl, 0); ndelay(t->low); out_8(&iic->directcntl, DIRCNTL_SCC); if (unlikely(iic_dc_wait(iic, DIRCNTL_MSC))) goto err; ndelay(t->su_sto); out_8(&iic->directcntl, DIRCNTL_SDAC | DIRCNTL_SCC); ndelay(t->buf); DBG("%d: smbus_quick -> %s\n", dev->idx, res ? "NACK" : "ACK"); out: /* Remove reset */ out_8(&iic->xtcntlss, 0); /* Reinitialize interface */ iic_dev_init(dev); return res; err: DBG("%d: smbus_quick - bus is stuck\n", dev->idx); res = -EREMOTEIO; goto out; } /* * IIC interrupt handler */ static irqreturn_t iic_handler(int irq, void *dev_id) { struct ibm_iic_private* dev = (struct ibm_iic_private*)dev_id; volatile struct iic_regs __iomem *iic = dev->vaddr; DBG2("%d: irq handler, STS = 0x%02x, EXTSTS = 0x%02x\n", dev->idx, in_8(&iic->sts), in_8(&iic->extsts)); /* Acknowledge IRQ and wakeup iic_wait_for_tc */ out_8(&iic->sts, STS_IRQA | STS_SCMP); wake_up_interruptible(&dev->wq); return IRQ_HANDLED; } /* * Get master transfer result and clear errors if any. * Returns the number of actually transferred bytes or error (<0) */ static int iic_xfer_result(struct ibm_iic_private* dev) { volatile struct iic_regs __iomem *iic = dev->vaddr; if (unlikely(in_8(&iic->sts) & STS_ERR)){ DBG("%d: xfer error, EXTSTS = 0x%02x\n", dev->idx, in_8(&iic->extsts)); /* Clear errors and possible pending IRQs */ out_8(&iic->extsts, EXTSTS_IRQP | EXTSTS_IRQD | EXTSTS_LA | EXTSTS_ICT | EXTSTS_XFRA); /* Flush master data buffer */ out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB); /* Is bus free? * If error happened during combined xfer * IIC interface is usually stuck in some strange * state, the only way out - soft reset. */ if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){ DBG("%d: bus is stuck, resetting\n", dev->idx); iic_dev_reset(dev); } return -EREMOTEIO; } else return in_8(&iic->xfrcnt) & XFRCNT_MTC_MASK; } /* * Try to abort active transfer. */ static void iic_abort_xfer(struct ibm_iic_private* dev) { volatile struct iic_regs __iomem *iic = dev->vaddr; unsigned long x; DBG("%d: iic_abort_xfer\n", dev->idx); out_8(&iic->cntl, CNTL_HMT); /* * Wait for the abort command to complete. * It's not worth to be optimized, just poll (timeout >= 1 tick) */ x = jiffies + 2; while ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){ if (time_after(jiffies, x)){ DBG("%d: abort timeout, resetting...\n", dev->idx); iic_dev_reset(dev); return; } schedule(); } /* Just to clear errors */ iic_xfer_result(dev); } /* * Wait for master transfer to complete. * It puts current process to sleep until we get interrupt or timeout expires. * Returns the number of transferred bytes or error (<0) */ static int iic_wait_for_tc(struct ibm_iic_private* dev){ volatile struct iic_regs __iomem *iic = dev->vaddr; int ret = 0; if (dev->irq >= 0){ /* Interrupt mode */ ret = wait_event_interruptible_timeout(dev->wq, !(in_8(&iic->sts) & STS_PT), dev->adap.timeout); if (unlikely(ret < 0)) DBG("%d: wait interrupted\n", dev->idx); else if (unlikely(in_8(&iic->sts) & STS_PT)){ DBG("%d: wait timeout\n", dev->idx); ret = -ETIMEDOUT; } } else { /* Polling mode */ unsigned long x = jiffies + dev->adap.timeout; while (in_8(&iic->sts) & STS_PT){ if (unlikely(time_after(jiffies, x))){ DBG("%d: poll timeout\n", dev->idx); ret = -ETIMEDOUT; break; } if (unlikely(signal_pending(current))){ DBG("%d: poll interrupted\n", dev->idx); ret = -ERESTARTSYS; break; } schedule(); } } if (unlikely(ret < 0)) iic_abort_xfer(dev); else ret = iic_xfer_result(dev); DBG2("%d: iic_wait_for_tc -> %d\n", dev->idx, ret); return ret; } /* * Low level master transfer routine */ static int iic_xfer_bytes(struct ibm_iic_private* dev, struct i2c_msg* pm, int combined_xfer) { volatile struct iic_regs __iomem *iic = dev->vaddr; char* buf = pm->buf; int i, j, loops, ret = 0; int len = pm->len; u8 cntl = (in_8(&iic->cntl) & CNTL_AMD) | CNTL_PT; if (pm->flags & I2C_M_RD) cntl |= CNTL_RW; loops = (len + 3) / 4; for (i = 0; i < loops; ++i, len -= 4){ int count = len > 4 ? 4 : len; u8 cmd = cntl | ((count - 1) << CNTL_TCT_SHIFT); if (!(cntl & CNTL_RW)) for (j = 0; j < count; ++j) out_8((void __iomem *)&iic->mdbuf, *buf++); if (i < loops - 1) cmd |= CNTL_CHT; else if (combined_xfer) cmd |= CNTL_RPST; DBG2("%d: xfer_bytes, %d, CNTL = 0x%02x\n", dev->idx, count, cmd); /* Start transfer */ out_8(&iic->cntl, cmd); /* Wait for completion */ ret = iic_wait_for_tc(dev); if (unlikely(ret < 0)) break; else if (unlikely(ret != count)){ DBG("%d: xfer_bytes, requested %d, transferred %d\n", dev->idx, count, ret); /* If it's not a last part of xfer, abort it */ if (combined_xfer || (i < loops - 1)) iic_abort_xfer(dev); ret = -EREMOTEIO; break; } if (cntl & CNTL_RW) for (j = 0; j < count; ++j) *buf++ = in_8((void __iomem *)&iic->mdbuf); } return ret > 0 ? 0 : ret; } /* * Set target slave address for master transfer */ static inline void iic_address(struct ibm_iic_private* dev, struct i2c_msg* msg) { volatile struct iic_regs __iomem *iic = dev->vaddr; u16 addr = msg->addr; DBG2("%d: iic_address, 0x%03x (%d-bit)\n", dev->idx, addr, msg->flags & I2C_M_TEN ? 10 : 7); if (msg->flags & I2C_M_TEN){ out_8(&iic->cntl, CNTL_AMD); out_8(&iic->lmadr, addr); out_8(&iic->hmadr, 0xf0 | ((addr >> 7) & 0x06)); } else { out_8(&iic->cntl, 0); out_8(&iic->lmadr, addr << 1); } } static inline int iic_invalid_address(const struct i2c_msg* p) { return (p->addr > 0x3ff) || (!(p->flags & I2C_M_TEN) && (p->addr > 0x7f)); } static inline int iic_address_neq(const struct i2c_msg* p1, const struct i2c_msg* p2) { return (p1->addr != p2->addr) || ((p1->flags & I2C_M_TEN) != (p2->flags & I2C_M_TEN)); } /* * Generic master transfer entrypoint. * Returns the number of processed messages or error (<0) */ static int iic_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) { struct ibm_iic_private* dev = (struct ibm_iic_private*)(i2c_get_adapdata(adap)); volatile struct iic_regs __iomem *iic = dev->vaddr; int i, ret = 0; DBG2("%d: iic_xfer, %d msg(s)\n", dev->idx, num); if (!num) return 0; /* Check the sanity of the passed messages. * Uhh, generic i2c layer is more suitable place for such code... */ if (unlikely(iic_invalid_address(&msgs[0]))){ DBG("%d: invalid address 0x%03x (%d-bit)\n", dev->idx, msgs[0].addr, msgs[0].flags & I2C_M_TEN ? 10 : 7); return -EINVAL; } for (i = 0; i < num; ++i){ if (unlikely(msgs[i].len <= 0)){ if (num == 1 && !msgs[0].len){ /* Special case for I2C_SMBUS_QUICK emulation. * IBM IIC doesn't support 0-length transactions * so we have to emulate them using bit-banging. */ return iic_smbus_quick(dev, &msgs[0]); } DBG("%d: invalid len %d in msg[%d]\n", dev->idx, msgs[i].len, i); return -EINVAL; } if (unlikely(iic_address_neq(&msgs[0], &msgs[i]))){ DBG("%d: invalid addr in msg[%d]\n", dev->idx, i); return -EINVAL; } } /* Check bus state */ if (unlikely((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE)){ DBG("%d: iic_xfer, bus is not free\n", dev->idx); /* Usually it means something serious has happened. * We *cannot* have unfinished previous transfer * so it doesn't make any sense to try to stop it. * Probably we were not able to recover from the * previous error. * The only *reasonable* thing I can think of here * is soft reset. --ebs */ iic_dev_reset(dev); if ((in_8(&iic->extsts) & EXTSTS_BCS_MASK) != EXTSTS_BCS_FREE){ DBG("%d: iic_xfer, bus is still not free\n", dev->idx); return -EREMOTEIO; } } else { /* Flush master data buffer (just in case) */ out_8(&iic->mdcntl, in_8(&iic->mdcntl) | MDCNTL_FMDB); } /* Load slave address */ iic_address(dev, &msgs[0]); /* Do real transfer */ for (i = 0; i < num && !ret; ++i) ret = iic_xfer_bytes(dev, &msgs[i], i < num - 1); return ret < 0 ? ret : num; } static u32 iic_func(struct i2c_adapter *adap) { return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR; } static const struct i2c_algorithm iic_algo = { .master_xfer = iic_xfer, .functionality = iic_func }; /* * Calculates IICx_CLCKDIV value for a specific OPB clock frequency */ static inline u8 iic_clckdiv(unsigned int opb) { /* Compatibility kludge, should go away after all cards * are fixed to fill correct value for opbfreq. * Previous driver version used hardcoded divider value 4, * it corresponds to OPB frequency from the range (40, 50] MHz */ if (!opb){ printk(KERN_WARNING "ibm-iic: using compatibility value for OPB freq," " fix your board specific setup\n"); opb = 50000000; } /* Convert to MHz */ opb /= 1000000; if (opb < 20 || opb > 150){ printk(KERN_WARNING "ibm-iic: invalid OPB clock frequency %u MHz\n", opb); opb = opb < 20 ? 20 : 150; } return (u8)((opb + 9) / 10 - 1); } static int iic_request_irq(struct platform_device *ofdev, struct ibm_iic_private *dev) { struct device_node *np = ofdev->dev.of_node; int irq; if (iic_force_poll) return 0; irq = irq_of_parse_and_map(np, 0); if (!irq) { dev_err(&ofdev->dev, "irq_of_parse_and_map failed\n"); return 0; } /* Disable interrupts until we finish initialization, assumes * level-sensitive IRQ setup... */ iic_interrupt_mode(dev, 0); if (request_irq(irq, iic_handler, 0, "IBM IIC", dev)) { dev_err(&ofdev->dev, "request_irq %d failed\n", irq); /* Fallback to the polling mode */ return 0; } return irq; } /* * Register single IIC interface */ static int iic_probe(struct platform_device *ofdev) { struct device_node *np = ofdev->dev.of_node; struct ibm_iic_private *dev; struct i2c_adapter *adap; const u32 *freq; int ret; dev = kzalloc(sizeof(*dev), GFP_KERNEL); if (!dev) { dev_err(&ofdev->dev, "failed to allocate device data\n"); return -ENOMEM; } dev_set_drvdata(&ofdev->dev, dev); dev->vaddr = of_iomap(np, 0); if (dev->vaddr == NULL) { dev_err(&ofdev->dev, "failed to iomap device\n"); ret = -ENXIO; goto error_cleanup; } init_waitqueue_head(&dev->wq); dev->irq = iic_request_irq(ofdev, dev); if (!dev->irq) dev_warn(&ofdev->dev, "using polling mode\n"); /* Board specific settings */ if (iic_force_fast || of_get_property(np, "fast-mode", NULL)) dev->fast_mode = 1; freq = of_get_property(np, "clock-frequency", NULL); if (freq == NULL) { freq = of_get_property(np->parent, "clock-frequency", NULL); if (freq == NULL) { dev_err(&ofdev->dev, "Unable to get bus frequency\n"); ret = -EINVAL; goto error_cleanup; } } dev->clckdiv = iic_clckdiv(*freq); dev_dbg(&ofdev->dev, "clckdiv = %d\n", dev->clckdiv); /* Initialize IIC interface */ iic_dev_init(dev); /* Register it with i2c layer */ adap = &dev->adap; adap->dev.parent = &ofdev->dev; adap->dev.of_node = of_node_get(np); strlcpy(adap->name, "IBM IIC", sizeof(adap->name)); i2c_set_adapdata(adap, dev); adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD; adap->algo = &iic_algo; adap->timeout = HZ; ret = i2c_add_adapter(adap); if (ret < 0) { dev_err(&ofdev->dev, "failed to register i2c adapter\n"); goto error_cleanup; } dev_info(&ofdev->dev, "using %s mode\n", dev->fast_mode ? "fast (400 kHz)" : "standard (100 kHz)"); /* Now register all the child nodes */ of_i2c_register_devices(adap); return 0; error_cleanup: if (dev->irq) { iic_interrupt_mode(dev, 0); free_irq(dev->irq, dev); } if (dev->vaddr) iounmap(dev->vaddr); kfree(dev); return ret; } /* * Cleanup initialized IIC interface */ static int iic_remove(struct platform_device *ofdev) { struct ibm_iic_private *dev = dev_get_drvdata(&ofdev->dev); i2c_del_adapter(&dev->adap); if (dev->irq) { iic_interrupt_mode(dev, 0); free_irq(dev->irq, dev); } iounmap(dev->vaddr); kfree(dev); return 0; } static const struct of_device_id ibm_iic_match[] = { { .compatible = "ibm,iic", }, {} }; static struct platform_driver ibm_iic_driver = { .driver = { .name = "ibm-iic", .owner = THIS_MODULE, .of_match_table = ibm_iic_match, }, .probe = iic_probe, .remove = iic_remove, }; module_platform_driver(ibm_iic_driver);