i2c: octeon: Cleanup i2c-octeon driver

Cleanup only without functional change.

- removed DRV_VERSION
- defines: use defines instead of plain values,
  use BIT_ULL macro, add comments
- rename waitqueue return value to time_left
- sort local variables by length
- fix indentation and whitespace errors
- make function return void if the result is not used
  (octeon_i2c_stop, octeon_i2c_set_clock)
- remove debug code from octeon_i2c_stop
- renamed some functions for readability
- update copyright
Signed-off-by: NJan Glauber <jglauber@cavium.com>
Signed-off-by: NWolfram Sang <wsa@the-dreams.de>

drivers/i2c/busses/i2c-octeon.c

@@ -2,7 +2,7 @@
  * (C) Copyright 2009-2010
  * Nokia Siemens Networks, michael.lawnick.ext@nsn.com
  *
- * Portions Copyright (C) 2010, 2011 Cavium Networks, Inc.
+ * Portions Copyright (C) 2010 - 2016 Cavium, Inc.
  *
  * This is a driver for the i2c adapter in Cavium Networks' OCTEON processors.
  *
@@ -26,39 +26,48 @@
 
 #define DRV_NAME "i2c-octeon"
 
-/* The previous out-of-tree version was implicitly version 1.0. */
-#define DRV_VERSION	"2.0"
-
-/* register offsets */
-#define SW_TWSI	 0x00
-#define TWSI_INT 0x10
+/* Register offsets */
+#define SW_TWSI			0x00
+#define TWSI_INT		0x10
 
 /* Controller command patterns */
-#define SW_TWSI_V               0x8000000000000000ull
-#define SW_TWSI_EOP_TWSI_DATA   0x0C00000100000000ull
-#define SW_TWSI_EOP_TWSI_CTL    0x0C00000200000000ull
-#define SW_TWSI_EOP_TWSI_CLKCTL 0x0C00000300000000ull
-#define SW_TWSI_EOP_TWSI_STAT   0x0C00000300000000ull
-#define SW_TWSI_EOP_TWSI_RST    0x0C00000700000000ull
-#define SW_TWSI_OP_TWSI_CLK     0x0800000000000000ull
-#define SW_TWSI_R               0x0100000000000000ull
+#define SW_TWSI_V		BIT_ULL(63)	/* Valid bit */
+#define SW_TWSI_R		BIT_ULL(56)	/* Result or read bit */
+
+/* Controller opcode word (bits 60:57) */
+#define SW_TWSI_OP_SHIFT	57
+#define SW_TWSI_OP_TWSI_CLK	(4ULL << SW_TWSI_OP_SHIFT)
+#define SW_TWSI_OP_EOP		(6ULL << SW_TWSI_OP_SHIFT) /* Extended opcode */
+
+/* Controller extended opcode word (bits 34:32) */
+#define SW_TWSI_EOP_SHIFT	32
+#define SW_TWSI_EOP_TWSI_DATA	(SW_TWSI_OP_EOP | 1ULL << SW_TWSI_EOP_SHIFT)
+#define SW_TWSI_EOP_TWSI_CTL	(SW_TWSI_OP_EOP | 2ULL << SW_TWSI_EOP_SHIFT)
+#define SW_TWSI_EOP_TWSI_CLKCTL	(SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
+#define SW_TWSI_EOP_TWSI_STAT	(SW_TWSI_OP_EOP | 3ULL << SW_TWSI_EOP_SHIFT)
+#define SW_TWSI_EOP_TWSI_RST	(SW_TWSI_OP_EOP | 7ULL << SW_TWSI_EOP_SHIFT)
 
 /* Controller command and status bits */
-#define TWSI_CTL_CE   0x80
-#define TWSI_CTL_ENAB 0x40
-#define TWSI_CTL_STA  0x20
-#define TWSI_CTL_STP  0x10
-#define TWSI_CTL_IFLG 0x08
-#define TWSI_CTL_AAK  0x04
+#define TWSI_CTL_CE		0x80
+#define TWSI_CTL_ENAB		0x40	/* Bus enable */
+#define TWSI_CTL_STA		0x20	/* Master-mode start, HW clears when done */
+#define TWSI_CTL_STP		0x10	/* Master-mode stop, HW clears when done */
+#define TWSI_CTL_IFLG		0x08	/* HW event, SW writes 0 to ACK */
+#define TWSI_CTL_AAK		0x04	/* Assert ACK */
 
 /* Some status values */
-#define STAT_START      0x08
-#define STAT_RSTART     0x10
-#define STAT_TXADDR_ACK 0x18
-#define STAT_TXDATA_ACK 0x28
-#define STAT_RXADDR_ACK 0x40
-#define STAT_RXDATA_ACK 0x50
-#define STAT_IDLE       0xF8
+#define STAT_START		0x08
+#define STAT_RSTART		0x10
+#define STAT_TXADDR_ACK		0x18
+#define STAT_TXDATA_ACK		0x28
+#define STAT_RXADDR_ACK		0x40
+#define STAT_RXDATA_ACK		0x50
+#define STAT_IDLE		0xF8
+
+/* TWSI_INT values */
+#define TWSI_INT_CORE_EN	BIT_ULL(6)
+#define TWSI_INT_SDA_OVR	BIT_ULL(8)
+#define TWSI_INT_SCL_OVR	BIT_ULL(9)
 
 struct octeon_i2c {
 	wait_queue_head_t queue;
@@ -80,9 +89,7 @@ struct octeon_i2c {
  *
  * The I2C core registers are accessed indirectly via the SW_TWSI CSR.
  */
-static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
-				u64 eop_reg,
-				u8 data)
+static void octeon_i2c_write_sw(struct octeon_i2c *i2c, u64 eop_reg, u8 data)
 {
 	u64 tmp;
 
@@ -93,7 +100,7 @@ static void octeon_i2c_write_sw(struct octeon_i2c *i2c,
 }
 
 /**
- * octeon_i2c_read_sw - write an I2C core register
+ * octeon_i2c_read_sw - read lower bits of an I2C core register
  * @i2c: The struct octeon_i2c
  * @eop_reg: Register selector
  *
@@ -133,12 +140,13 @@ static void octeon_i2c_write_int(struct octeon_i2c *i2c, u64 data)
  */
 static void octeon_i2c_int_enable(struct octeon_i2c *i2c)
 {
-	octeon_i2c_write_int(i2c, 0x40);
+	octeon_i2c_write_int(i2c, TWSI_INT_CORE_EN);
 }
 
 /* disable the CORE interrupt */
 static void octeon_i2c_int_disable(struct octeon_i2c *i2c)
 {
+	/* clear TS/ST/IFLG events */
 	octeon_i2c_write_int(i2c, 0);
 }
 
@@ -154,17 +162,19 @@ static void octeon_i2c_unblock(struct octeon_i2c *i2c)
 	int i;
 
 	dev_dbg(i2c->dev, "%s\n", __func__);
+
 	for (i = 0; i < 9; i++) {
-		octeon_i2c_write_int(i2c, 0x0);
+		octeon_i2c_write_int(i2c, 0);
 		udelay(5);
-		octeon_i2c_write_int(i2c, 0x200);
+		octeon_i2c_write_int(i2c, TWSI_INT_SCL_OVR);
 		udelay(5);
 	}
-	octeon_i2c_write_int(i2c, 0x300);
+	/* hand-crank a STOP */
+	octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR | TWSI_INT_SCL_OVR);
 	udelay(5);
-	octeon_i2c_write_int(i2c, 0x100);
+	octeon_i2c_write_int(i2c, TWSI_INT_SDA_OVR);
 	udelay(5);
-	octeon_i2c_write_int(i2c, 0x0);
+	octeon_i2c_write_int(i2c, 0);
 }
 
 /* interrupt service routine */
@@ -192,17 +202,13 @@ static int octeon_i2c_test_iflg(struct octeon_i2c *i2c)
  */
 static int octeon_i2c_wait(struct octeon_i2c *i2c)
 {
-	long result;
+	long time_left;
 
 	octeon_i2c_int_enable(i2c);
-
-	result = wait_event_timeout(i2c->queue,
-					octeon_i2c_test_iflg(i2c),
-					i2c->adap.timeout);
-
+	time_left = wait_event_timeout(i2c->queue, octeon_i2c_test_iflg(i2c),
+				       i2c->adap.timeout);
 	octeon_i2c_int_disable(i2c);
-
-	if (result == 0) {
+	if (!time_left) {
 		dev_dbg(i2c->dev, "%s: timeout\n", __func__);
 		return -ETIMEDOUT;
 	}
@@ -218,11 +224,11 @@ static int octeon_i2c_wait(struct octeon_i2c *i2c)
  */
 static int octeon_i2c_start(struct octeon_i2c *i2c)
 {
-	u8 data;
 	int result;
+	u8 data;
 
 	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
-				TWSI_CTL_ENAB | TWSI_CTL_STA);
+			    TWSI_CTL_ENAB | TWSI_CTL_STA);
 
 	result = octeon_i2c_wait(i2c);
 	if (result) {
@@ -235,7 +241,6 @@ static int octeon_i2c_start(struct octeon_i2c *i2c)
 			octeon_i2c_unblock(i2c);
 			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
 					    TWSI_CTL_ENAB | TWSI_CTL_STA);
-
 			result = octeon_i2c_wait(i2c);
 		}
 		if (result)
@@ -251,26 +256,11 @@ static int octeon_i2c_start(struct octeon_i2c *i2c)
 	return 0;
 }
 
-/**
- * octeon_i2c_stop - send STOP to the bus
- * @i2c: The struct octeon_i2c
- *
- * Returns 0 on success, otherwise a negative errno.
- */
-static int octeon_i2c_stop(struct octeon_i2c *i2c)
+/* send STOP to the bus */
+static void octeon_i2c_stop(struct octeon_i2c *i2c)
 {
-	u8 data;
-
 	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
 			    TWSI_CTL_ENAB | TWSI_CTL_STP);
-
-	data = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
-
-	if (data != STAT_IDLE) {
-		dev_err(i2c->dev, "%s: bad status(0x%x)\n", __func__, data);
-		return -EIO;
-	}
-	return 0;
 }
 
 /**
@@ -303,6 +293,7 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
 
 	for (i = 0; i < length; i++) {
 		tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+
 		if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
 			dev_err(i2c->dev,
 				"%s: bad status before write (0x%x)\n",
@@ -345,7 +336,7 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 	if (result)
 		return result;
 
-	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target<<1) | 1);
+	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_DATA, (target << 1) | 1);
 	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL, TWSI_CTL_ENAB);
 
 	result = octeon_i2c_wait(i2c);
@@ -354,6 +345,7 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 
 	for (i = 0; i < length; i++) {
 		tmp = octeon_i2c_read_sw(i2c, SW_TWSI_EOP_TWSI_STAT);
+
 		if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
 			dev_err(i2c->dev,
 				"%s: bad status before read (0x%x)\n",
@@ -361,12 +353,12 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 			return -EIO;
 		}
 
-		if (i+1 < length)
+		if (i + 1 < length)
 			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
-						TWSI_CTL_ENAB | TWSI_CTL_AAK);
+					    TWSI_CTL_ENAB | TWSI_CTL_AAK);
 		else
 			octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CTL,
-						TWSI_CTL_ENAB);
+					    TWSI_CTL_ENAB);
 
 		result = octeon_i2c_wait(i2c);
 		if (result)
@@ -385,27 +377,25 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
  *
  * Returns the number of messages processed, or a negative errno on failure.
  */
-static int octeon_i2c_xfer(struct i2c_adapter *adap,
-			   struct i2c_msg *msgs,
+static int octeon_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			   int num)
 {
-	struct i2c_msg *pmsg;
-	int i;
-	int ret = 0;
 	struct octeon_i2c *i2c = i2c_get_adapdata(adap);
+	int i, ret = 0;
 
 	for (i = 0; ret == 0 && i < num; i++) {
-		pmsg = &msgs[i];
+		struct i2c_msg *pmsg = &msgs[i];
+
 		dev_dbg(i2c->dev,
 			"Doing %s %d byte(s) to/from 0x%02x - %d of %d messages\n",
 			 pmsg->flags & I2C_M_RD ? "read" : "write",
 			 pmsg->len, pmsg->addr, i + 1, num);
 		if (pmsg->flags & I2C_M_RD)
 			ret = octeon_i2c_read(i2c, pmsg->addr, pmsg->buf,
-						pmsg->len);
+					      pmsg->len);
 		else
 			ret = octeon_i2c_write(i2c, pmsg->addr, pmsg->buf,
-						pmsg->len);
+					       pmsg->len);
 	}
 	octeon_i2c_stop(i2c);
 
@@ -430,7 +420,7 @@ static struct i2c_adapter octeon_i2c_ops = {
 };
 
 /* calculate and set clock divisors */
-static int octeon_i2c_setclock(struct octeon_i2c *i2c)
+static void octeon_i2c_set_clock(struct octeon_i2c *i2c)
 {
 	int tclk, thp_base, inc, thp_idx, mdiv_idx, ndiv_idx, foscl, diff;
 	int thp = 0x18, mdiv = 2, ndiv = 0, delta_hz = 1000000;
@@ -438,8 +428,7 @@ static int octeon_i2c_setclock(struct octeon_i2c *i2c)
 	for (ndiv_idx = 0; ndiv_idx < 8 && delta_hz != 0; ndiv_idx++) {
 		/*
 		 * An mdiv value of less than 2 seems to not work well
-		 * with ds1337 RTCs, so we constrain it to larger
-		 * values.
+		 * with ds1337 RTCs, so we constrain it to larger values.
 		 */
 		for (mdiv_idx = 15; mdiv_idx >= 2 && delta_hz != 0; mdiv_idx--) {
 			/*
@@ -449,6 +438,7 @@ static int octeon_i2c_setclock(struct octeon_i2c *i2c)
 			tclk = i2c->twsi_freq * (mdiv_idx + 1) * 10;
 			tclk *= (1 << ndiv_idx);
 			thp_base = (i2c->sys_freq / (tclk * 2)) - 1;
+
 			for (inc = 0; inc <= 1; inc++) {
 				thp_idx = thp_base + inc;
 				if (thp_idx < 5 || thp_idx > 0xff)
@@ -469,11 +459,9 @@ static int octeon_i2c_setclock(struct octeon_i2c *i2c)
 	}
 	octeon_i2c_write_sw(i2c, SW_TWSI_OP_TWSI_CLK, thp);
 	octeon_i2c_write_sw(i2c, SW_TWSI_EOP_TWSI_CLKCTL, (mdiv << 3) | ndiv);
-
-	return 0;
 }
 
-static int octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
+static int octeon_i2c_init_lowlevel(struct octeon_i2c *i2c)
 {
 	u8 status;
 	int tries;
@@ -496,9 +484,10 @@ static int octeon_i2c_initlowlevel(struct octeon_i2c *i2c)
 
 static int octeon_i2c_probe(struct platform_device *pdev)
 {
-	int irq, result = 0;
-	struct octeon_i2c *i2c;
+	struct device_node *node = pdev->dev.of_node;
 	struct resource *res_mem;
+	struct octeon_i2c *i2c;
+	int irq, result = 0;
 
 	/* All adaptors have an irq.  */
 	irq = platform_get_irq(pdev, 0);
@@ -507,7 +496,6 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 
 	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
 	if (!i2c) {
-		dev_err(&pdev->dev, "kzalloc failed\n");
 		result = -ENOMEM;
 		goto out;
 	}
@@ -528,10 +516,8 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 	 * "clock-frequency".  Try the official one first and then
 	 * fall back if it doesn't exist.
 	 */
-	if (of_property_read_u32(pdev->dev.of_node,
-				 "clock-frequency", &i2c->twsi_freq) &&
-	    of_property_read_u32(pdev->dev.of_node,
-				 "clock-rate", &i2c->twsi_freq)) {
+	if (of_property_read_u32(node, "clock-frequency", &i2c->twsi_freq) &&
+	    of_property_read_u32(node, "clock-rate", &i2c->twsi_freq)) {
 		dev_err(i2c->dev,
 			"no I2C 'clock-rate' or 'clock-frequency' property\n");
 		result = -ENXIO;
@@ -541,7 +527,7 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 	i2c->sys_freq = octeon_get_io_clock_rate();
 
 	if (!devm_request_mem_region(&pdev->dev, i2c->twsi_phys, i2c->regsize,
-				      res_mem->name)) {
+				     res_mem->name)) {
 		dev_err(i2c->dev, "request_mem_region failed\n");
 		goto out;
 	}
@@ -558,21 +544,17 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 		goto out;
 	}
 
-	result = octeon_i2c_initlowlevel(i2c);
+	result = octeon_i2c_init_lowlevel(i2c);
 	if (result) {
 		dev_err(i2c->dev, "init low level failed\n");
 		goto  out;
 	}
 
-	result = octeon_i2c_setclock(i2c);
-	if (result) {
-		dev_err(i2c->dev, "clock init failed\n");
-		goto  out;
-	}
+	octeon_i2c_set_clock(i2c);
 
 	i2c->adap = octeon_i2c_ops;
 	i2c->adap.dev.parent = &pdev->dev;
-	i2c->adap.dev.of_node = pdev->dev.of_node;
+	i2c->adap.dev.of_node = node;
 	i2c_set_adapdata(&i2c->adap, i2c);
 	platform_set_drvdata(pdev, i2c);
 
@@ -581,8 +563,7 @@ static int octeon_i2c_probe(struct platform_device *pdev)
 		dev_err(i2c->dev, "failed to add adapter\n");
 		goto out;
 	}
-	dev_info(i2c->dev, "version %s\n", DRV_VERSION);
-
+	dev_info(i2c->dev, "probed\n");
 	return 0;
 
 out:
@@ -597,10 +578,8 @@ static int octeon_i2c_remove(struct platform_device *pdev)
 	return 0;
 };
 
-static struct of_device_id octeon_i2c_match[] = {
-	{
-		.compatible = "cavium,octeon-3860-twsi",
-	},
+static const struct of_device_id octeon_i2c_match[] = {
+	{ .compatible = "cavium,octeon-3860-twsi", },
 	{},
 };
 MODULE_DEVICE_TABLE(of, octeon_i2c_match);
@@ -619,4 +598,3 @@ module_platform_driver(octeon_i2c_driver);
 MODULE_AUTHOR("Michael Lawnick <michael.lawnick.ext@nsn.com>");
 MODULE_DESCRIPTION("I2C-Bus adapter for Cavium OCTEON processors");
 MODULE_LICENSE("GPL");
-MODULE_VERSION(DRV_VERSION);