diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-ocores.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-ocores.c | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c new file mode 100644 index 00000000000..592824087c4 --- /dev/null +++ b/drivers/i2c/busses/i2c-ocores.c @@ -0,0 +1,341 @@ +/* + * i2c-ocores.c: I2C bus driver for OpenCores I2C controller + * (http://www.opencores.org/projects.cgi/web/i2c/overview). + * + * Peter Korsgaard <jacmet@sunsite.dk> + * + * This file is licensed under the terms of the GNU General Public License + * version 2. This program is licensed "as is" without any warranty of any + * kind, whether express or implied. + */ + +#include <linux/config.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/sched.h> +#include <linux/init.h> +#include <linux/errno.h> +#include <linux/platform_device.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/wait.h> +#include <linux/i2c-ocores.h> +#include <asm/io.h> + +struct ocores_i2c { + void __iomem *base; + int regstep; + wait_queue_head_t wait; + struct i2c_adapter adap; + struct i2c_msg *msg; + int pos; + int nmsgs; + int state; /* see STATE_ */ +}; + +/* registers */ +#define OCI2C_PRELOW 0 +#define OCI2C_PREHIGH 1 +#define OCI2C_CONTROL 2 +#define OCI2C_DATA 3 +#define OCI2C_CMD 4 /* write only */ +#define OCI2C_STATUS 4 /* read only, same address as OCI2C_CMD */ + +#define OCI2C_CTRL_IEN 0x40 +#define OCI2C_CTRL_EN 0x80 + +#define OCI2C_CMD_START 0x91 +#define OCI2C_CMD_STOP 0x41 +#define OCI2C_CMD_READ 0x21 +#define OCI2C_CMD_WRITE 0x11 +#define OCI2C_CMD_READ_ACK 0x21 +#define OCI2C_CMD_READ_NACK 0x29 +#define OCI2C_CMD_IACK 0x01 + +#define OCI2C_STAT_IF 0x01 +#define OCI2C_STAT_TIP 0x02 +#define OCI2C_STAT_ARBLOST 0x20 +#define OCI2C_STAT_BUSY 0x40 +#define OCI2C_STAT_NACK 0x80 + +#define STATE_DONE 0 +#define STATE_START 1 +#define STATE_WRITE 2 +#define STATE_READ 3 +#define STATE_ERROR 4 + +static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value) +{ + iowrite8(value, i2c->base + reg * i2c->regstep); +} + +static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg) +{ + return ioread8(i2c->base + reg * i2c->regstep); +} + +static void ocores_process(struct ocores_i2c *i2c) +{ + struct i2c_msg *msg = i2c->msg; + u8 stat = oc_getreg(i2c, OCI2C_STATUS); + + if ((i2c->state == STATE_DONE) || (i2c->state == STATE_ERROR)) { + /* stop has been sent */ + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); + wake_up(&i2c->wait); + return; + } + + /* error? */ + if (stat & OCI2C_STAT_ARBLOST) { + i2c->state = STATE_ERROR; + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); + return; + } + + if ((i2c->state == STATE_START) || (i2c->state == STATE_WRITE)) { + i2c->state = + (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE; + + if (stat & OCI2C_STAT_NACK) { + i2c->state = STATE_ERROR; + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); + return; + } + } else + msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA); + + /* end of msg? */ + if (i2c->pos == msg->len) { + i2c->nmsgs--; + i2c->msg++; + i2c->pos = 0; + msg = i2c->msg; + + if (i2c->nmsgs) { /* end? */ + /* send start? */ + if (!(msg->flags & I2C_M_NOSTART)) { + u8 addr = (msg->addr << 1); + + if (msg->flags & I2C_M_RD) + addr |= 1; + + i2c->state = STATE_START; + + oc_setreg(i2c, OCI2C_DATA, addr); + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); + return; + } else + i2c->state = (msg->flags & I2C_M_RD) + ? STATE_READ : STATE_WRITE; + } else { + i2c->state = STATE_DONE; + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); + return; + } + } + + if (i2c->state == STATE_READ) { + oc_setreg(i2c, OCI2C_CMD, i2c->pos == (msg->len-1) ? + OCI2C_CMD_READ_NACK : OCI2C_CMD_READ_ACK); + } else { + oc_setreg(i2c, OCI2C_DATA, msg->buf[i2c->pos++]); + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_WRITE); + } +} + +static irqreturn_t ocores_isr(int irq, void *dev_id, struct pt_regs *regs) +{ + struct ocores_i2c *i2c = dev_id; + + ocores_process(i2c); + + return IRQ_HANDLED; +} + +static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) +{ + struct ocores_i2c *i2c = i2c_get_adapdata(adap); + + i2c->msg = msgs; + i2c->pos = 0; + i2c->nmsgs = num; + i2c->state = STATE_START; + + oc_setreg(i2c, OCI2C_DATA, + (i2c->msg->addr << 1) | + ((i2c->msg->flags & I2C_M_RD) ? 1:0)); + + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); + + if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) || + (i2c->state == STATE_DONE), HZ)) + return (i2c->state == STATE_DONE) ? num : -EIO; + else + return -ETIMEDOUT; +} + +static void ocores_init(struct ocores_i2c *i2c, + struct ocores_i2c_platform_data *pdata) +{ + int prescale; + u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); + + /* make sure the device is disabled */ + oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + + prescale = (pdata->clock_khz / (5*100)) - 1; + oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff); + oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8); + + /* Init the device */ + oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); + oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN); +} + + +static u32 ocores_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static struct i2c_algorithm ocores_algorithm = { + .master_xfer = ocores_xfer, + .functionality = ocores_func, +}; + +static struct i2c_adapter ocores_adapter = { + .owner = THIS_MODULE, + .name = "i2c-ocores", + .class = I2C_CLASS_HWMON, + .algo = &ocores_algorithm, +}; + + +static int __devinit ocores_i2c_probe(struct platform_device *pdev) +{ + struct ocores_i2c *i2c; + struct ocores_i2c_platform_data *pdata; + struct resource *res, *res2; + int ret; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENODEV; + + res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (!res2) + return -ENODEV; + + pdata = (struct ocores_i2c_platform_data*) pdev->dev.platform_data; + if (!pdata) + return -ENODEV; + + i2c = kzalloc(sizeof(*i2c), GFP_KERNEL); + if (!i2c) + return -ENOMEM; + + if (!request_mem_region(res->start, res->end - res->start + 1, + pdev->name)) { + dev_err(&pdev->dev, "Memory region busy\n"); + ret = -EBUSY; + goto request_mem_failed; + } + + i2c->base = ioremap(res->start, res->end - res->start + 1); + if (!i2c->base) { + dev_err(&pdev->dev, "Unable to map registers\n"); + ret = -EIO; + goto map_failed; + } + + i2c->regstep = pdata->regstep; + ocores_init(i2c, pdata); + + init_waitqueue_head(&i2c->wait); + ret = request_irq(res2->start, ocores_isr, 0, pdev->name, i2c); + if (ret) { + dev_err(&pdev->dev, "Cannot claim IRQ\n"); + goto request_irq_failed; + } + + /* hook up driver to tree */ + platform_set_drvdata(pdev, i2c); + i2c->adap = ocores_adapter; + i2c_set_adapdata(&i2c->adap, i2c); + i2c->adap.dev.parent = &pdev->dev; + + /* add i2c adapter to i2c tree */ + ret = i2c_add_adapter(&i2c->adap); + if (ret) { + dev_err(&pdev->dev, "Failed to add adapter\n"); + goto add_adapter_failed; + } + + return 0; + +add_adapter_failed: + free_irq(res2->start, i2c); +request_irq_failed: + iounmap(i2c->base); +map_failed: + release_mem_region(res->start, res->end - res->start + 1); +request_mem_failed: + kfree(i2c); + + return ret; +} + +static int __devexit ocores_i2c_remove(struct platform_device* pdev) +{ + struct ocores_i2c *i2c = platform_get_drvdata(pdev); + struct resource *res; + + /* disable i2c logic */ + oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL) + & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + + /* remove adapter & data */ + i2c_del_adapter(&i2c->adap); + platform_set_drvdata(pdev, NULL); + + res = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (res) + free_irq(res->start, i2c); + + iounmap(i2c->base); + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (res) + release_mem_region(res->start, res->end - res->start + 1); + + kfree(i2c); + + return 0; +} + +static struct platform_driver ocores_i2c_driver = { + .probe = ocores_i2c_probe, + .remove = __devexit_p(ocores_i2c_remove), + .driver = { + .owner = THIS_MODULE, + .name = "ocores-i2c", + }, +}; + +static int __init ocores_i2c_init(void) +{ + return platform_driver_register(&ocores_i2c_driver); +} + +static void __exit ocores_i2c_exit(void) +{ + platform_driver_unregister(&ocores_i2c_driver); +} + +module_init(ocores_i2c_init); +module_exit(ocores_i2c_exit); + +MODULE_AUTHOR("Peter Korsgaard <jacmet@sunsite.dk>"); +MODULE_DESCRIPTION("OpenCores I2C bus driver"); +MODULE_LICENSE("GPL"); |