text: /*
   * drivers/i2c/busses/i2c-s6000.c
   *
   * Description: Driver for S6000 Family I2C Interface
   * Copyright (c) 2008 emlix GmbH
   * Author:	Oskar Schirmer <oskar@scara.com>
   *
   * Partially based on i2c-bfin-twi.c driver by <sonic.zhang@analog.com>
   * Copyright (c) 2005-2007 Analog Devices, Inc.
   *
   * 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.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/i2c.h>
  #include <linux/i2c/s6000.h>
  #include <linux/timer.h>
  #include <linux/spinlock.h>
  #include <linux/completion.h>
  #include <linux/interrupt.h>
  #include <linux/platform_device.h>
  #include <linux/io.h>
  
  #include "i2c-s6000.h"
  
  #define DRV_NAME "i2c-s6000"
  
  #define POLL_TIMEOUT	(2 * HZ)
  
  struct s6i2c_if {
  	u8 __iomem		*reg; /* memory mapped registers */
  	int			irq;
  	spinlock_t		lock;
  	struct i2c_msg		*msgs; /* messages currently handled */
  	int			msgs_num; /* nb of msgs to do */
  	int			msgs_push; /* nb of msgs read/written */
  	int			msgs_done; /* nb of msgs finally handled */
  	unsigned		push; /* nb of bytes read/written in msg */
  	unsigned		done; /* nb of bytes finally handled */
  	int			timeout_count; /* timeout retries left */
  	struct timer_list	timeout_timer;
  	struct i2c_adapter	adap;
  	struct completion	complete;
  	struct clk		*clk;
  	struct resource		*res;
  };
  
  static inline u16 i2c_rd16(struct s6i2c_if *iface, unsigned n)
  {
  	return readw(iface->reg + (n));
  }
  
  static inline void i2c_wr16(struct s6i2c_if *iface, unsigned n, u16 v)
  {
  	writew(v, iface->reg + (n));
  }
  
  static inline u32 i2c_rd32(struct s6i2c_if *iface, unsigned n)
  {
  	return readl(iface->reg + (n));
  }
  
  static inline void i2c_wr32(struct s6i2c_if *iface, unsigned n, u32 v)
  {
  	writel(v, iface->reg + (n));
  }
  
  static struct s6i2c_if s6i2c_if;
  
  static void s6i2c_handle_interrupt(struct s6i2c_if *iface)
  {
  	if (i2c_rd16(iface, S6_I2C_INTRSTAT) & (1 << S6_I2C_INTR_TXABRT)) {
  		i2c_rd16(iface, S6_I2C_CLRTXABRT);
  		i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  		complete(&iface->complete);
  		return;
  	}
  	if (iface->msgs_done >= iface->msgs_num) {
  		dev_err(&iface->adap.dev, "s6i2c: spurious I2C irq: %04x\n",
  			i2c_rd16(iface, S6_I2C_INTRSTAT));
  		i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  		return;
  	}
  	while ((iface->msgs_push < iface->msgs_num)
  	    && (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_TFNF))) {
  		struct i2c_msg *m = &iface->msgs[iface->msgs_push];
  		if (!(m->flags & I2C_M_RD))
  			i2c_wr16(iface, S6_I2C_DATACMD, m->buf[iface->push]);
  		else
  			i2c_wr16(iface, S6_I2C_DATACMD,
  				 1 << S6_I2C_DATACMD_READ);
  		if (++iface->push >= m->len) {
  			iface->push = 0;
  			iface->msgs_push += 1;
  		}
  	}
  	do {
  		struct i2c_msg *m = &iface->msgs[iface->msgs_done];
  		if (!(m->flags & I2C_M_RD)) {
  			if (iface->msgs_done < iface->msgs_push)
  				iface->msgs_done += 1;
  			else
  				break;
  		} else if (i2c_rd16(iface, S6_I2C_STATUS)
  				& (1 << S6_I2C_STATUS_RFNE)) {
  			m->buf[iface->done] = i2c_rd16(iface, S6_I2C_DATACMD);
  			if (++iface->done >= m->len) {
  				iface->done = 0;
  				iface->msgs_done += 1;
  			}
  		} else{
  			break;
  		}
  	} while (iface->msgs_done < iface->msgs_num);
  	if (iface->msgs_done >= iface->msgs_num) {
  		i2c_wr16(iface, S6_I2C_INTRMASK, 1 << S6_I2C_INTR_TXABRT);
  		complete(&iface->complete);
  	} else if (iface->msgs_push >= iface->msgs_num) {
  		i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
  						 (1 << S6_I2C_INTR_RXFULL));
  	} else {
  		i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
  						 (1 << S6_I2C_INTR_TXEMPTY) |
  						 (1 << S6_I2C_INTR_RXFULL));
  	}
  }
  
  static irqreturn_t s6i2c_interrupt_entry(int irq, void *dev_id)
  {
  	struct s6i2c_if *iface = dev_id;
  	if (!(i2c_rd16(iface, S6_I2C_STATUS) & ((1 << S6_I2C_INTR_RXUNDER)
  					      | (1 << S6_I2C_INTR_RXOVER)
  					      | (1 << S6_I2C_INTR_RXFULL)
  					      | (1 << S6_I2C_INTR_TXOVER)
  					      | (1 << S6_I2C_INTR_TXEMPTY)
  					      | (1 << S6_I2C_INTR_RDREQ)
  					      | (1 << S6_I2C_INTR_TXABRT)
  					      | (1 << S6_I2C_INTR_RXDONE)
  					      | (1 << S6_I2C_INTR_ACTIVITY)
  					      | (1 << S6_I2C_INTR_STOPDET)
  					      | (1 << S6_I2C_INTR_STARTDET)
  					      | (1 << S6_I2C_INTR_GENCALL))))
  		return IRQ_NONE;
  
  	spin_lock(&iface->lock);
  	del_timer(&iface->timeout_timer);
  	s6i2c_handle_interrupt(iface);
  	spin_unlock(&iface->lock);
  	return IRQ_HANDLED;
  }
  
  static void s6i2c_timeout(unsigned long data)
  {
  	struct s6i2c_if *iface = (struct s6i2c_if *)data;
  	unsigned long flags;
  
  	spin_lock_irqsave(&iface->lock, flags);
  	s6i2c_handle_interrupt(iface);
  	if (--iface->timeout_count > 0) {
  		iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
  		add_timer(&iface->timeout_timer);
  	} else {
  		complete(&iface->complete);
  		i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  	}
  	spin_unlock_irqrestore(&iface->lock, flags);
  }
  
  static int s6i2c_master_xfer(struct i2c_adapter *adap,
  				struct i2c_msg *msgs, int num)
  {
  	struct s6i2c_if *iface = adap->algo_data;
  	int i;
  	if (num == 0)
  		return 0;
  	if (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
  		yield();
  	i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  	i2c_rd16(iface, S6_I2C_CLRINTR);
  	for (i = 0; i < num; i++) {
  		if (msgs[i].flags & I2C_M_TEN) {
  			dev_err(&adap->dev,
  				"s6i2c: 10 bits addr not supported\n");
  			return -EINVAL;
  		}
  		if (msgs[i].len == 0) {
  			dev_err(&adap->dev,
  				"s6i2c: zero length message not supported\n");
  			return -EINVAL;
  		}
  		if (msgs[i].addr != msgs[0].addr) {
  			dev_err(&adap->dev,
  				"s6i2c: multiple xfer cannot change target\n");
  			return -EINVAL;
  		}
  	}
  
  	iface->msgs = msgs;
  	iface->msgs_num = num;
  	iface->msgs_push = 0;
  	iface->msgs_done = 0;
  	iface->push = 0;
  	iface->done = 0;
  	iface->timeout_count = 10;
  	i2c_wr16(iface, S6_I2C_TAR, msgs[0].addr);
  	i2c_wr16(iface, S6_I2C_ENABLE, 1);
  	i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXEMPTY) |
  					 (1 << S6_I2C_INTR_TXABRT));
  
  	iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
  	add_timer(&iface->timeout_timer);
  	wait_for_completion(&iface->complete);
  	del_timer_sync(&iface->timeout_timer);
  	while (i2c_rd32(iface, S6_I2C_TXFLR) > 0)
  		schedule();
  	while (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
  		schedule();
  
  	i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  	i2c_wr16(iface, S6_I2C_ENABLE, 0);
  	return iface->msgs_done;
  }
  
  static u32 s6i2c_functionality(struct i2c_adapter *adap)
  {
  	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
  }
  
  static struct i2c_algorithm s6i2c_algorithm = {
  	.master_xfer   = s6i2c_master_xfer,
  	.functionality = s6i2c_functionality,
  };
  
  static u16 __devinit nanoseconds_on_clk(struct s6i2c_if *iface, u32 ns)
  {
  	u32 dividend = ((clk_get_rate(iface->clk) / 1000) * ns) / 1000000;
  	if (dividend > 0xffff)
  		return 0xffff;
  	return dividend;
  }
  
  static int __devinit s6i2c_probe(struct platform_device *dev)
  {
  	struct s6i2c_if *iface = &s6i2c_if;
  	struct i2c_adapter *p_adap;
  	const char *clock;
  	int bus_num, rc;
  	spin_lock_init(&iface->lock);
  	init_completion(&iface->complete);
  	iface->irq = platform_get_irq(dev, 0);
  	if (iface->irq < 0) {
  		rc = iface->irq;
  		goto err_out;
  	}
  	iface->res = platform_get_resource(dev, IORESOURCE_MEM, 0);
  	if (!iface->res) {
  		rc = -ENXIO;
  		goto err_out;
  	}
  	iface->res = request_mem_region(iface->res->start,
  					resource_size(iface->res),
  					dev->dev.bus_id);
  	if (!iface->res) {
  		rc = -EBUSY;
  		goto err_out;
  	}
  	iface->reg = ioremap_nocache(iface->res->start,
  				     resource_size(iface->res));
  	if (!iface->reg) {
  		rc = -ENOMEM;
  		goto err_reg;
  	}
  
  	clock = 0;
  	bus_num = -1;
  	if (dev->dev.platform_data) {
  		struct s6_i2c_platform_data *pdata = dev->dev.platform_data;
  		bus_num = pdata->bus_num;
  		clock = pdata->clock;
  	}
  	iface->clk = clk_get(&dev->dev, clock);
  	if (IS_ERR(iface->clk)) {
  		rc = PTR_ERR(iface->clk);
  		goto err_map;
  	}
  	rc = clk_enable(iface->clk);
  	if (rc < 0)
  		goto err_clk_put;
  	init_timer(&iface->timeout_timer);
  	iface->timeout_timer.function = s6i2c_timeout;
  	iface->timeout_timer.data = (unsigned long)iface;
  
  	p_adap = &iface->adap;
  	strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
  	p_adap->algo = &s6i2c_algorithm;
  	p_adap->algo_data = iface;
  	p_adap->nr = bus_num;
  	p_adap->class = 0;
  	p_adap->dev.parent = &dev->dev;
  	i2c_wr16(iface, S6_I2C_INTRMASK, 0);
  	rc = request_irq(iface->irq, s6i2c_interrupt_entry,
  			 IRQF_SHARED, dev->name, iface);
  	if (rc) {
  		dev_err(&p_adap->dev, "s6i2c: can't get IRQ %d\n", iface->irq);
  		goto err_clk_dis;
  	}
  
  	i2c_wr16(iface, S6_I2C_ENABLE, 0);
  	udelay(1);
  	i2c_wr32(iface, S6_I2C_SRESET, 1 << S6_I2C_SRESET_IC_SRST);
  	i2c_wr16(iface, S6_I2C_CLRTXABRT, 1);
  	i2c_wr16(iface, S6_I2C_CON,
  			(1 << S6_I2C_CON_MASTER) |
  			(S6_I2C_CON_SPEED_NORMAL << S6_I2C_CON_SPEED) |
  			(0 << S6_I2C_CON_10BITSLAVE) |
  			(0 << S6_I2C_CON_10BITMASTER) |
  			(1 << S6_I2C_CON_RESTARTENA) |
  			(1 << S6_I2C_CON_SLAVEDISABLE));
  	i2c_wr16(iface, S6_I2C_SSHCNT, nanoseconds_on_clk(iface, 4000));
  	i2c_wr16(iface, S6_I2C_SSLCNT, nanoseconds_on_clk(iface, 4700));
  	i2c_wr16(iface, S6_I2C_FSHCNT, nanoseconds_on_clk(iface, 600));
  	i2c_wr16(iface, S6_I2C_FSLCNT, nanoseconds_on_clk(iface, 1300));
  	i2c_wr16(iface, S6_I2C_RXTL, 0);
  	i2c_wr16(iface, S6_I2C_TXTL, 0);
  
  	platform_set_drvdata(dev, iface);
  	rc = i2c_add_numbered_adapter(p_adap);
  	if (rc)
  		goto err_irq_free;
  	return 0;
  
  err_irq_free:
  	free_irq(iface->irq, iface);
  err_clk_dis:
  	clk_disable(iface->clk);
  err_clk_put:
  	clk_put(iface->clk);
  err_map:
  	iounmap(iface->reg);
  err_reg:
  	release_mem_region(iface->res->start,
  			   resource_size(iface->res));
  err_out:
  	return rc;
  }
  
  static int __devexit s6i2c_remove(struct platform_device *pdev)
  {
  	struct s6i2c_if *iface = platform_get_drvdata(pdev);
  	i2c_wr16(iface, S6_I2C_ENABLE, 0);
  	platform_set_drvdata(pdev, NULL);
  	i2c_del_adapter(&iface->adap);
  	free_irq(iface->irq, iface);
  	clk_disable(iface->clk);
  	clk_put(iface->clk);
  	iounmap(iface->reg);
  	release_mem_region(iface->res->start,
  			   resource_size(iface->res));
  	return 0;
  }
  
  static struct platform_driver s6i2c_driver = {
  	.probe		= s6i2c_probe,
  	.remove		= __devexit_p(s6i2c_remove),
  	.driver		= {
  		.name	= DRV_NAME,
  		.owner	= THIS_MODULE,
  	},
  };
  
  static int __init s6i2c_init(void)
  {
  	pr_info("I2C: S6000 I2C driver\n");
  	return platform_driver_register(&s6i2c_driver);
  }
  
  static void __exit s6i2c_exit(void)
  {
  	platform_driver_unregister(&s6i2c_driver);
  }
  
  MODULE_DESCRIPTION("I2C-Bus adapter routines for S6000 I2C");
  MODULE_LICENSE("GPL");
  MODULE_ALIAS("platform:" DRV_NAME);
  
  subsys_initcall(s6i2c_init);
  module_exit(s6i2c_exit);
  