diff options
| -rw-r--r-- | drivers/i2c/busses/Kconfig | 7 | ||||
| -rw-r--r-- | drivers/i2c/busses/Makefile | 1 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-at91.c | 325 |
3 files changed, 333 insertions, 0 deletions
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index 291da25..ab398b7 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -74,6 +74,13 @@ config I2C_AMD8111 This driver can also be built as a module. If so, the module will be called i2c-amd8111. +config I2C_AT91 + tristate "Atmel AT91 I2C Two-Wire interface (TWI)" + depends on I2C && ARCH_AT91 && EXPERIMENTAL + help + This supports the use of the I2C interface on Atmel AT91 + processors. + config I2C_AU1550 tristate "Au1550/Au1200 SMBus interface" depends on I2C && (SOC_AU1550 || SOC_AU1200) diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile index 626ac71..a82b6bf 100644 --- a/drivers/i2c/busses/Makefile +++ b/drivers/i2c/busses/Makefile @@ -8,6 +8,7 @@ obj-$(CONFIG_I2C_ALI15X3) += i2c-ali15x3.o obj-$(CONFIG_I2C_AMD756) += i2c-amd756.o obj-$(CONFIG_I2C_AMD756_S4882) += i2c-amd756-s4882.o obj-$(CONFIG_I2C_AMD8111) += i2c-amd8111.o +obj-$(CONFIG_I2C_AT91) += i2c-at91.o obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o obj-$(CONFIG_I2C_HYDRA) += i2c-hydra.o 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"); |