--- /dev/null
+--- a/drivers/i2c/busses/Kconfig
++++ b/drivers/i2c/busses/Kconfig
+@@ -282,7 +282,7 @@ comment "I2C system bus drivers (mostly
+
+ config I2C_AT91
+ tristate "Atmel AT91 I2C Two-Wire interface (TWI)"
+- depends on ARCH_AT91 && EXPERIMENTAL && BROKEN
++ depends on ARCH_AT91 && EXPERIMENTAL
+ help
+ This supports the use of the I2C interface on Atmel AT91
+ processors.
+--- a/drivers/i2c/busses/i2c-at91.c
++++ b/drivers/i2c/busses/i2c-at91.c
+@@ -11,8 +11,18 @@
+ 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.
++
++ D. Gilbert [20100318 AT91SAM9G20]
++ - Check for NACK, a NACK will abort current tranfser,
++ returned as errno=EREMOTEIO unless I2C_M_IGNORE_NAK is set
++ - Only supports 7 bit I2C device (slave) address
++ - clockrate adjustable (module_param).
+ */
+
++
++/* Uncomment following line to see dev_dbg() output in logs */
++/* #define DEBUG 1 */
++
+ #include <linux/module.h>
+ #include <linux/kernel.h>
+ #include <linux/err.h>
+@@ -32,26 +42,28 @@
+ #define TWI_CLOCK 100000 /* Hz. max 400 Kbits/sec */
+
+
++static unsigned int clockrate = TWI_CLOCK;
++static unsigned int prev_clockrate = TWI_CLOCK;
+ 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.
++ * Set TWI clock dividers based on clockrate (clock rate for SCL)
+ */
+-static void __devinit at91_twi_hwinit(void)
++static void at91_twi_clock_dividers(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 */
++ if (clockrate < 1000)
++ clockrate = 1000;
++ else if (clockrate > 400000)
++ clockrate = 400000;
+
+- /* Calcuate clock dividers */
+- cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3;
++ /* Calculate clock dividers */
++ cdiv = (clk_get_rate(twi_clk) / (2 * clockrate)) - 3;
+ cdiv = cdiv + 1; /* round up */
+ ckdiv = 0;
+ while (cdiv > 255) {
+@@ -61,41 +73,92 @@ static void __devinit at91_twi_hwinit(vo
+
+ if (cpu_is_at91rm9200()) { /* AT91RM9200 Errata #22 */
+ if (ckdiv > 5) {
+- printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n");
++ printk(KERN_ERR "i2c-at91: Invalid AT91RM9200 clock rate\n");
+ ckdiv = 5;
+ }
+ }
++ /* AT91SAM9G20 has 3 bits for ckdiv so it cannot exceed 7 */
++ if (cpu_is_at91sam9g20()) {
++ if (ckdiv > 7) {
++ printk(KERN_ERR "i2c-at91: Invalid AT91SAM9G20 clock "
++ "rate, ckdiv=%lu\n", ckdiv);
++ ckdiv = 7;
++ }
++ }
+
+ at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv);
++ prev_clockrate = clockrate;
+ }
+
+ /*
+- * Poll the i2c status register until the specified bit is set.
+- * Returns 0 if timed out (100 msec).
++ * Initialize the TWI hardware registers.
+ */
+-static short at91_poll_status(unsigned long bit)
++static void __devinit at91_twi_hwinit(void)
+ {
+- int loop_cntr = 10000;
++ at91_twi_write(AT91_TWI_IDR, 0xffffffff); /* Disable all interrupts */
++ at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST); /* Reset peripheral */
++ /* Set Master mode; Atmel suggests disabling slave mode */
++ at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN | AT91_TWI_SVDIS);
+
++ at91_twi_clock_dividers();
++}
++
++/*
++ * Poll the i2c status register until the specified bit is set or a NACK
++ * occurs. Returns 0 if timed out (50 msec). If nack_seen_p is non-NULL
++ * then write 0 to it first, then if the NACK bit is set in the status
++ * register then write 1 to it and immediately return with a value of 1.
++ */
++static short at91_poll_status(unsigned long bit, int * nack_seen_p)
++{
++ int loop_cntr = 5000;
++ unsigned long stat;
++
++ if (nack_seen_p)
++ *nack_seen_p = 0;
++ if (clockrate <= 20000)
++ loop_cntr = 100;
+ do {
+- udelay(10);
+- } while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0));
++ if (clockrate <= 20000)
++ udelay(100);
++ else if (clockrate <= 100000)
++ udelay(10);
++ else
++ udelay(3);
++ stat = at91_twi_read(AT91_TWI_SR);
++ if ((stat & AT91_TWI_NACK) && nack_seen_p) {
++ *nack_seen_p = 1;
++ return 1;
++ }
++ } while (!(stat & bit) && (--loop_cntr > 0));
+
+ return (loop_cntr > 0);
+ }
+
+ static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)
+ {
++ int nack_seen = 0;
++ int sent_stop = 0;
++
+ /* Send Start */
+- at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
++ if (1 == length) {
++ at91_twi_write(AT91_TWI_CR, AT91_TWI_START | AT91_TWI_STOP);
++ sent_stop = 1;
++ } else
++ at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
+
+ /* Read data */
+ while (length--) {
+- if (!length) /* need to send Stop before reading last byte */
++ /* send Stop before reading last byte (if not already done) */
++ if ((0 == length) && (0 == sent_stop))
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
+- if (!at91_poll_status(AT91_TWI_RXRDY)) {
++ if (!at91_poll_status(AT91_TWI_RXRDY, &nack_seen)) {
+ dev_dbg(&adap->dev, "RXRDY timeout\n");
+ return -ETIMEDOUT;
++ } else if (nack_seen) {
++ dev_dbg(&adap->dev, "read NACKed\n");
++ /* NACK supplies Stop */
++ return -EREMOTEIO;
+ }
+ *buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff);
+ }
+@@ -105,16 +168,24 @@ static int xfer_read(struct i2c_adapter
+
+ static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)
+ {
++ int nack_seen = 0;
++
+ /* Load first byte into transmitter */
+ at91_twi_write(AT91_TWI_THR, *buf++);
+
+- /* Send Start */
++ /* Send Start [AT91SAM9G20 does not need this on write] */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_START);
+
+ do {
+- if (!at91_poll_status(AT91_TWI_TXRDY)) {
++ if (!at91_poll_status(AT91_TWI_TXRDY, &nack_seen)) {
+ dev_dbg(&adap->dev, "TXRDY timeout\n");
++ /* Set Master mode again */
++ at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN);
+ return -ETIMEDOUT;
++ } else if (nack_seen) {
++ dev_dbg(&adap->dev, "write NACKed\n");
++ /* NACK supplies Stop */
++ return -EREMOTEIO;
+ }
+
+ length--; /* byte was transmitted */
+@@ -123,7 +194,7 @@ static int xfer_write(struct i2c_adapter
+ at91_twi_write(AT91_TWI_THR, *buf++);
+ } while (length);
+
+- /* Send Stop */
++ /* Send Stop [AT91SAM9G20 does not need this on write] */
+ at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);
+
+ return 0;
+@@ -136,11 +207,19 @@ static int xfer_write(struct i2c_adapter
+ * Instead the "internal device address" has to be written using a separate
+ * i2c message.
+ * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
++ * [dpg] By 2010 silicon bugs should be fixed, will need IADR for 10 bit device address
+ */
+ static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num)
+ {
+ int i, ret;
++ int nack_seen = 0;
+
++ if (prev_clockrate != clockrate) {
++ dev_dbg(&adap->dev, "at91_xfer: prev_clockrate=%u "
++ "clockrate=%u, change\n", prev_clockrate, clockrate);
++ at91_twi_clock_dividers();
++ msleep(1); /* let things settle */
++ }
+ dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
+
+ for (i = 0; i < num; i++) {
+@@ -158,13 +237,23 @@ static int at91_xfer(struct i2c_adapter
+ else
+ ret = xfer_write(adap, pmsg->buf, pmsg->len);
+
+- if (ret)
+- return ret;
+-
++ if (ret) {
++ if ((I2C_M_IGNORE_NAK & pmsg->flags) &&
++ (-EREMOTEIO == ret)) {
++ dev_dbg(&adap->dev, "transfer "
++ "NACKed, skip to next\n");
++ pmsg++;
++ continue;
++ } else
++ return ret;
++ }
+ /* Wait until transfer is finished */
+- if (!at91_poll_status(AT91_TWI_TXCOMP)) {
++ if (!at91_poll_status(AT91_TWI_TXCOMP, &nack_seen)) {
+ dev_dbg(&adap->dev, "TXCOMP timeout\n");
+ return -ETIMEDOUT;
++ } else if (nack_seen) {
++ dev_dbg(&adap->dev, "TXCOMP NACKed\n");
++ return -EREMOTEIO;
+ }
+ }
+ dev_dbg(&adap->dev, "transfer complete\n");
+@@ -239,7 +328,8 @@ static int __devinit at91_i2c_probe(stru
+ goto fail3;
+ }
+
+- dev_info(&pdev->dev, "AT91 i2c bus driver.\n");
++ dev_info(&pdev->dev, "AT91 TWI (I2C) bus driver [SCL %d Hz]\n",
++ clockrate);
+ return 0;
+
+ fail3:
+@@ -295,6 +385,11 @@ static int at91_i2c_resume(struct platfo
+ #define at91_i2c_resume NULL
+ #endif
+
++/* I2C clock speed, in Hz 0-400kHz*/
++module_param(clockrate, uint, S_IRUGO | S_IWUSR);
++MODULE_PARM_DESC(clockrate,
++ "SCL clock rate, 1000 to 400000 Hz (def: 100 kHz)");
++
+ /* work with "modprobe at91_i2c" from hotplugging or coldplugging */
+ MODULE_ALIAS("platform:at91_i2c");
+
+@@ -323,5 +418,5 @@ module_init(at91_i2c_init);
+ module_exit(at91_i2c_exit);
+
+ MODULE_AUTHOR("Rick Bronson");
+-MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
++MODULE_DESCRIPTION("I2C (TWI) master driver for Atmel AT91");
+ MODULE_LICENSE("GPL");
projects / openwrt / staging / rmilecki.git / commitdiff