i2c: New Atmel AT91 bus driver
Add support for the I2C (Two-wire interface) controller integrated in
the Atmel AT91RM9200 processor. This driver should also be usable on
the Atmel AT91SAM9261 and AT91SAM9260 processors.
Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
diff --git a/drivers/i2c/busses/i2c-at91.c b/drivers/i2c/busses/i2c-at91.c
new file mode 100644
index 0000000..67f91bd
--- /dev/null
+++ b/drivers/i2c/busses/i2c-at91.c
@@ -0,0 +1,325 @@
+/*
+ i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
+
+ Copyright (C) 2004 Rick Bronson
+ Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
+
+ Borrowed heavily from original work by:
+ Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
+
+ 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 <linux/module.h>
+#include <linux/version.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/types.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/clk.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+
+#include <asm/arch/at91_twi.h>
+#include <asm/arch/board.h>
+#include <asm/arch/cpu.h>
+
+#define TWI_CLOCK 100000 /* Hz. max 400 Kbits/sec */
+
+
+static struct clk *twi_clk;
+static void __iomem *twi_base;
+
+#define at91_twi_read(reg) __raw_readl(twi_base + (reg))
+#define at91_twi_write(reg, val) __raw_writel((val), twi_base + (reg))
+
+
+/*
+ * Initialize the TWI hardware registers.
+ */
+static void __devinit at91_twi_hwinit(void)
+{
+ unsigned long cdiv, ckdiv;
+
+ at91_twi_write(AT91_TWI_IDR, 0xffffffff); /* Disable all interrupts */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST); /* Reset peripheral */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN); /* Set Master mode */
+
+ /* Calcuate clock dividers */
+ cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3;
+ cdiv = cdiv + 1; /* round up */
+ ckdiv = 0;
+ while (cdiv > 255) {
+ ckdiv++;
+ cdiv = cdiv >> 1;
+ }
+
+ if (cpu_is_at91rm9200()) { /* AT91RM9200 Errata #22 */
+ if (ckdiv > 5) {
+ printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n");
+ ckdiv = 5;
+ }
+ }
+
+ at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv);
+}
+
+/*
+ * Poll the i2c status register until the specified bit is set.
+ * Returns 0 if timed out (100 msec).
+ */
+static short at91_poll_status(unsigned long bit)
+{
+ int loop_cntr = 10000;
+
+ do {
+ udelay(10);
+ } while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0));
+
+ return (loop_cntr > 0);
+}
+
+static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
+{
+ /* Send Start */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
+
+ /* Read data */
+ while (length--) {
+ if (!length) /* need to send Stop before reading last byte */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
+ if (!at91_poll_status(AT91_TWI_RXRDY)) {
+ dev_dbg(&adap->dev, "RXRDY timeout\n");
+ return -ETIMEDOUT;
+ }
+ *buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff);
+ }
+
+ return 0;
+}
+
+static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)
+{
+ /* Load first byte into transmitter */
+ at91_twi_write(AT91_TWI_THR, *buf++);
+
+ /* Send Start */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
+
+ do {
+ if (!at91_poll_status(AT91_TWI_TXRDY)) {
+ dev_dbg(&adap->dev, "TXRDY timeout\n");
+ return -ETIMEDOUT;
+ }
+
+ length--; /* byte was transmitted */
+
+ if (length > 0) /* more data to send? */
+ at91_twi_write(AT91_TWI_THR, *buf++);
+ } while (length);
+
+ /* Send Stop */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
+
+ return 0;
+}
+
+/*
+ * Generic i2c master transfer entrypoint.
+ *
+ * Note: We do not use Atmel's feature of storing the "internal device address".
+ * Instead the "internal device address" has to be written using a seperate
+ * i2c message.
+ * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
+ */
+static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num)
+{
+ int i, ret;
+
+ dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
+
+ for (i = 0; i < num; i++) {
+ dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i,
+ pmsg->flags & I2C_M_RD ? "read" : "writ",
+ pmsg->len, pmsg->len > 1 ? "s" : "",
+ pmsg->flags & I2C_M_RD ? "from" : "to", pmsg->addr);
+
+ at91_twi_write(AT91_TWI_MMR, (pmsg->addr << 16)
+ | ((pmsg->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
+
+ if (pmsg->len && pmsg->buf) { /* sanity check */
+ if (pmsg->flags & I2C_M_RD)
+ ret = xfer_read(adap, pmsg->buf, pmsg->len);
+ else
+ ret = xfer_write(adap, pmsg->buf, pmsg->len);
+
+ if (ret)
+ return ret;
+
+ /* Wait until transfer is finished */
+ if (!at91_poll_status(AT91_TWI_TXCOMP)) {
+ dev_dbg(&adap->dev, "TXCOMP timeout\n");
+ return -ETIMEDOUT;
+ }
+ }
+ dev_dbg(&adap->dev, "transfer complete\n");
+ pmsg++; /* next message */
+ }
+ return i;
+}
+
+/*
+ * Return list of supported functionality.
+ */
+static u32 at91_func(struct i2c_adapter *adapter)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm at91_algorithm = {
+ .master_xfer = at91_xfer,
+ .functionality = at91_func,
+};
+
+/*
+ * Main initialization routine.
+ */
+static int __devinit at91_i2c_probe(struct platform_device *pdev)
+{
+ struct i2c_adapter *adapter;
+ struct resource *res;
+ int rc;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ return -ENXIO;
+
+ if (!request_mem_region(res->start, res->end - res->start + 1, "at91_i2c"))
+ return -EBUSY;
+
+ twi_base = ioremap(res->start, res->end - res->start + 1);
+ if (!twi_base) {
+ rc = -ENOMEM;
+ goto fail0;
+ }
+
+ twi_clk = clk_get(NULL, "twi_clk");
+ if (IS_ERR(twi_clk)) {
+ dev_err(&pdev->dev, "no clock defined\n");
+ rc = -ENODEV;
+ goto fail1;
+ }
+
+ adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
+ if (adapter == NULL) {
+ dev_err(&pdev->dev, "can't allocate inteface!\n");
+ rc = -ENOMEM;
+ goto fail2;
+ }
+ sprintf(adapter->name, "AT91");
+ adapter->algo = &at91_algorithm;
+ adapter->class = I2C_CLASS_HWMON;
+ adapter->dev.parent = &pdev->dev;
+
+ platform_set_drvdata(pdev, adapter);
+
+ clk_enable(twi_clk); /* enable peripheral clock */
+ at91_twi_hwinit(); /* initialize TWI controller */
+
+ rc = i2c_add_adapter(adapter);
+ if (rc) {
+ dev_err(&pdev->dev, "Adapter %s registration failed\n",
+ adapter->name);
+ goto fail3;
+ }
+
+ dev_info(&pdev->dev, "AT91 i2c bus driver.\n");
+ return 0;
+
+fail3:
+ platform_set_drvdata(pdev, NULL);
+ kfree(adapter);
+ clk_disable(twi_clk);
+fail2:
+ clk_put(twi_clk);
+fail1:
+ iounmap(twi_base);
+fail0:
+ release_mem_region(res->start, res->end - res->start + 1);
+
+ return rc;
+}
+
+static int __devexit at91_i2c_remove(struct platform_device *pdev)
+{
+ struct i2c_adapter *adapter = platform_get_drvdata(pdev);
+ struct resource *res;
+ int rc;
+
+ rc = i2c_del_adapter(adapter);
+ platform_set_drvdata(pdev, NULL);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ iounmap(twi_base);
+ release_mem_region(res->start, res->end - res->start + 1);
+
+ clk_disable(twi_clk); /* disable peripheral clock */
+ clk_put(twi_clk);
+
+ return rc;
+}
+
+#ifdef CONFIG_PM
+
+/* NOTE: could save a few mA by keeping clock off outside of at91_xfer... */
+
+static int at91_i2c_suspend(struct platform_device *pdev, pm_message_t mesg)
+{
+ clk_disable(twi_clk);
+ return 0;
+}
+
+static int at91_i2c_resume(struct platform_device *pdev)
+{
+ return clk_enable(twi_clk);
+}
+
+#else
+#define at91_i2c_suspend NULL
+#define at91_i2c_resume NULL
+#endif
+
+static struct platform_driver at91_i2c_driver = {
+ .probe = at91_i2c_probe,
+ .remove = __devexit_p(at91_i2c_remove),
+ .suspend = at91_i2c_suspend,
+ .resume = at91_i2c_resume,
+ .driver = {
+ .name = "at91_i2c",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init at91_i2c_init(void)
+{
+ return platform_driver_register(&at91_i2c_driver);
+}
+
+static void __exit at91_i2c_exit(void)
+{
+ platform_driver_unregister(&at91_i2c_driver);
+}
+
+module_init(at91_i2c_init);
+module_exit(at91_i2c_exit);
+
+MODULE_AUTHOR("Rick Bronson");
+MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
+MODULE_LICENSE("GPL");