ks8851: Low level functions for read/write to companion eeprom

Low-level functions provide 16bits words read and write capability
to ks8851 companion eeprom.

Signed-off-by: Sebastien Jan <s-jan@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 241 insertions, 1 deletions

diff --git a/drivers/net/ks8851.c b/drivers/net/ks8851.c
index 623171f37d9..3dba57b72ef 100644
--- a/drivers/net/ks8851.c
+++ b/drivers/net/ks8851.c
@@ -1034,6 +1034,234 @@ static const struct net_device_ops ks8851_netdev_ops = {
 	.ndo_validate_addr	= eth_validate_addr,
 };
 
+/* Companion eeprom access */
+
+enum {	/* EEPROM programming states */
+	EEPROM_CONTROL,
+	EEPROM_ADDRESS,
+	EEPROM_DATA,
+	EEPROM_COMPLETE
+};
+
+/**
+ * ks8851_eeprom_read - read a 16bits word in ks8851 companion EEPROM
+ * @dev: The network device the PHY is on.
+ * @addr: EEPROM address to read
+ *
+ * eeprom_size: used to define the data coding length. Can be changed
+ * through debug-fs.
+ *
+ * Programs a read on the EEPROM using ks8851 EEPROM SW access feature.
+ * Warning: The READ feature is not supported on ks8851 revision 0.
+ *
+ * Rough programming model:
+ *  - on period start: set clock high and read value on bus
+ *  - on period / 2: set clock low and program value on bus
+ *  - start on period / 2
+ */
+unsigned int ks8851_eeprom_read(struct net_device *dev, unsigned int addr)
+{
+	struct ks8851_net *ks = netdev_priv(dev);
+	int eepcr;
+	int ctrl = EEPROM_OP_READ;
+	int state = EEPROM_CONTROL;
+	int bit_count = EEPROM_OP_LEN - 1;
+	unsigned int data = 0;
+	int dummy;
+	unsigned int addr_len;
+
+	addr_len = (ks->eeprom_size == 128) ? 6 : 8;
+
+	/* start transaction: chip select high, authorize write */
+	mutex_lock(&ks->lock);
+	eepcr = EEPCR_EESA | EEPCR_EESRWA;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	eepcr |= EEPCR_EECS;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	mutex_unlock(&ks->lock);
+
+	while (state != EEPROM_COMPLETE) {
+		/* falling clock period starts... */
+		/* set EED_IO pin for control and address */
+		eepcr &= ~EEPCR_EEDO;
+		switch (state) {
+		case EEPROM_CONTROL:
+			eepcr |= ((ctrl >> bit_count) & 1) << 2;
+			if (bit_count-- <= 0) {
+				bit_count = addr_len - 1;
+				state = EEPROM_ADDRESS;
+			}
+			break;
+		case EEPROM_ADDRESS:
+			eepcr |= ((addr >> bit_count) & 1) << 2;
+			bit_count--;
+			break;
+		case EEPROM_DATA:
+			/* Change to receive mode */
+			eepcr &= ~EEPCR_EESRWA;
+			break;
+		}
+
+		/* lower clock  */
+		eepcr &= ~EEPCR_EESCK;
+
+		mutex_lock(&ks->lock);
+		ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+		mutex_unlock(&ks->lock);
+
+		/* waitread period / 2 */
+		udelay(EEPROM_SK_PERIOD / 2);
+
+		/* rising clock period starts... */
+
+		/* raise clock */
+		mutex_lock(&ks->lock);
+		eepcr |= EEPCR_EESCK;
+		ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+		mutex_unlock(&ks->lock);
+
+		/* Manage read */
+		switch (state) {
+		case EEPROM_ADDRESS:
+			if (bit_count < 0) {
+				bit_count = EEPROM_DATA_LEN - 1;
+				state = EEPROM_DATA;
+			}
+			break;
+		case EEPROM_DATA:
+			mutex_lock(&ks->lock);
+			dummy = ks8851_rdreg16(ks, KS_EEPCR);
+			mutex_unlock(&ks->lock);
+			data |= ((dummy >> EEPCR_EESB_OFFSET) & 1) << bit_count;
+			if (bit_count-- <= 0)
+				state = EEPROM_COMPLETE;
+			break;
+		}
+
+		/* wait period / 2 */
+		udelay(EEPROM_SK_PERIOD / 2);
+	}
+
+	/* close transaction */
+	mutex_lock(&ks->lock);
+	eepcr &= ~EEPCR_EECS;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	eepcr = 0;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	mutex_unlock(&ks->lock);
+
+	return data;
+}
+
+/**
+ * ks8851_eeprom_write - write a 16bits word in ks8851 companion EEPROM
+ * @dev: The network device the PHY is on.
+ * @op: operand (can be WRITE, EWEN, EWDS)
+ * @addr: EEPROM address to write
+ * @data: data to write
+ *
+ * eeprom_size: used to define the data coding length. Can be changed
+ * through debug-fs.
+ *
+ * Programs a write on the EEPROM using ks8851 EEPROM SW access feature.
+ *
+ * Note that a write enable is required before writing data.
+ *
+ * Rough programming model:
+ *  - on period start: set clock high
+ *  - on period / 2: set clock low and program value on bus
+ *  - start on period / 2
+ */
+void ks8851_eeprom_write(struct net_device *dev, unsigned int op,
+					unsigned int addr, unsigned int data)
+{
+	struct ks8851_net *ks = netdev_priv(dev);
+	int eepcr;
+	int state = EEPROM_CONTROL;
+	int bit_count = EEPROM_OP_LEN - 1;
+	unsigned int addr_len;
+
+	addr_len = (ks->eeprom_size == 128) ? 6 : 8;
+
+	switch (op) {
+	case EEPROM_OP_EWEN:
+		addr = 0x30;
+	break;
+	case EEPROM_OP_EWDS:
+		addr = 0;
+		break;
+	}
+
+	/* start transaction: chip select high, authorize write */
+	mutex_lock(&ks->lock);
+	eepcr = EEPCR_EESA | EEPCR_EESRWA;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	eepcr |= EEPCR_EECS;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	mutex_unlock(&ks->lock);
+
+	while (state != EEPROM_COMPLETE) {
+		/* falling clock period starts... */
+		/* set EED_IO pin for control and address */
+		eepcr &= ~EEPCR_EEDO;
+		switch (state) {
+		case EEPROM_CONTROL:
+			eepcr |= ((op >> bit_count) & 1) << 2;
+			if (bit_count-- <= 0) {
+				bit_count = addr_len - 1;
+				state = EEPROM_ADDRESS;
+			}
+			break;
+		case EEPROM_ADDRESS:
+			eepcr |= ((addr >> bit_count) & 1) << 2;
+			if (bit_count-- <= 0) {
+				if (op == EEPROM_OP_WRITE) {
+					bit_count = EEPROM_DATA_LEN - 1;
+					state = EEPROM_DATA;
+				} else {
+					state = EEPROM_COMPLETE;
+				}
+			}
+			break;
+		case EEPROM_DATA:
+			eepcr |= ((data >> bit_count) & 1) << 2;
+			if (bit_count-- <= 0)
+				state = EEPROM_COMPLETE;
+			break;
+		}
+
+		/* lower clock  */
+		eepcr &= ~EEPCR_EESCK;
+
+		mutex_lock(&ks->lock);
+		ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+		mutex_unlock(&ks->lock);
+
+		/* wait period / 2 */
+		udelay(EEPROM_SK_PERIOD / 2);
+
+		/* rising clock period starts... */
+
+		/* raise clock */
+		eepcr |= EEPCR_EESCK;
+		mutex_lock(&ks->lock);
+		ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+		mutex_unlock(&ks->lock);
+
+		/* wait period / 2 */
+		udelay(EEPROM_SK_PERIOD / 2);
+	}
+
+	/* close transaction */
+	mutex_lock(&ks->lock);
+	eepcr &= ~EEPCR_EECS;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	eepcr = 0;
+	ks8851_wrreg16(ks, KS_EEPCR, eepcr);
+	mutex_unlock(&ks->lock);
+
+}
+
 /* ethtool support */
 
 static void ks8851_get_drvinfo(struct net_device *dev,
diff --git a/drivers/net/ks8851.h b/drivers/net/ks8851.h
index f52c312cc35..537fb06e593 100644
--- a/drivers/net/ks8851.h
+++ b/drivers/net/ks8851.h
@@ -25,12 +25,24 @@
 #define OBCR_ODS_16mA				(1 << 6)
 
 #define KS_EEPCR				0x22
+#define EEPCR_EESRWA				(1 << 5)
 #define EEPCR_EESA				(1 << 4)
-#define EEPCR_EESB				(1 << 3)
+#define EEPCR_EESB_OFFSET			3
+#define EEPCR_EESB				(1 << EEPCR_EESB_OFFSET)
 #define EEPCR_EEDO				(1 << 2)
 #define EEPCR_EESCK				(1 << 1)
 #define EEPCR_EECS				(1 << 0)
 
+#define EEPROM_OP_LEN				3	/* bits:*/
+#define EEPROM_OP_READ				0x06
+#define EEPROM_OP_EWEN				0x04
+#define EEPROM_OP_WRITE				0x05
+#define EEPROM_OP_EWDS				0x14
+
+#define EEPROM_DATA_LEN				16	/* 16 bits EEPROM */
+#define EEPROM_WRITE_TIME			4	/* wrt ack time in ms */
+#define EEPROM_SK_PERIOD			400	/* in us */
+
 #define KS_MBIR					0x24
 #define MBIR_TXMBF				(1 << 12)
 #define MBIR_TXMBFA				(1 << 11)