lan743x: Provide Read/Write Access to on chip OTP

The LAN743x includes on chip One-Time-Programmable (OTP) memory.

This patch extends the ethtool EEPROM read/write interface to
access OTP memory space.

The currently existing interface is limited, as it does not
allow OTP read, and OTP writes are restricted to
offset==0, length==512, and data[0]==0xF3.

This patch removes these restrictions and adds a private flag
called OTP_ACCESS, which is used to switch between EEPROM, and
OTP modes.

The private flag OTP_ACCESS is configurable through the
  ethtool --set-priv-flags command.
And visible through the
  ethtool --show-priv-flags command.

By default OTP_ACCESS is false, and there for previously existing
EEPROM commands will work exactly the same. However now access to
OTP requires one extra step of setting OTP_ACCESS to true. This
flag controls the read, write, and length reporting, functions
of ethtool.

EEPROM presence is not checked when setting or clearing this flag.
If the EEPROM is not present, the user, as before, will need to
diagnose that using existing read and write function of ethtool,
while OTP_ACCESS is false.

Updates for V2:
Added comments as to why this patch is needed.
Added comments explaining that EEPROM presence is not check
  when setting or clearing the OTP_ACCESS flag.
Added length checking to all otp/eeprom read/write functions.

Signed-off-by: Bryan Whitehead <Bryan.Whitehead@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 170 insertions, 47 deletions

diff --git a/drivers/net/ethernet/microchip/lan743x_ethtool.c b/drivers/net/ethernet/microchip/lan743x_ethtool.c
index 07c1eb63415a..3a0b289d9771 100644
--- a/drivers/net/ethernet/microchip/lan743x_ethtool.c
+++ b/drivers/net/ethernet/microchip/lan743x_ethtool.c
@@ -14,61 +14,138 @@
 #define EEPROM_INDICATOR_1		    (0xA5)
 #define EEPROM_INDICATOR_2		    (0xAA)
 #define EEPROM_MAC_OFFSET		    (0x01)
-#define MAX_EEPROM_SIZE			    512
+#define MAX_EEPROM_SIZE			    (512)
+#define MAX_OTP_SIZE			    (1024)
 #define OTP_INDICATOR_1			    (0xF3)
 #define OTP_INDICATOR_2			    (0xF7)
 
-static int lan743x_otp_write(struct lan743x_adapter *adapter, u32 offset,
-			     u32 length, u8 *data)
+static int lan743x_otp_power_up(struct lan743x_adapter *adapter)
+{
+	u32 reg_value;
+
+	reg_value = lan743x_csr_read(adapter, OTP_PWR_DN);
+
+	if (reg_value & OTP_PWR_DN_PWRDN_N_) {
+		/* clear it and wait to be cleared */
+		reg_value &= ~OTP_PWR_DN_PWRDN_N_;
+		lan743x_csr_write(adapter, OTP_PWR_DN, reg_value);
+
+		usleep_range(100, 20000);
+	}
+
+	return 0;
+}
+
+static void lan743x_otp_power_down(struct lan743x_adapter *adapter)
+{
+	u32 reg_value;
+
+	reg_value = lan743x_csr_read(adapter, OTP_PWR_DN);
+	if (!(reg_value & OTP_PWR_DN_PWRDN_N_)) {
+		/* set power down bit */
+		reg_value |= OTP_PWR_DN_PWRDN_N_;
+		lan743x_csr_write(adapter, OTP_PWR_DN, reg_value);
+	}
+}
+
+static void lan743x_otp_set_address(struct lan743x_adapter *adapter,
+				    u32 address)
+{
+	lan743x_csr_write(adapter, OTP_ADDR_HIGH, (address >> 8) & 0x03);
+	lan743x_csr_write(adapter, OTP_ADDR_LOW, address & 0xFF);
+}
+
+static void lan743x_otp_read_go(struct lan743x_adapter *adapter)
+{
+	lan743x_csr_write(adapter, OTP_FUNC_CMD, OTP_FUNC_CMD_READ_);
+	lan743x_csr_write(adapter, OTP_CMD_GO, OTP_CMD_GO_GO_);
+}
+
+static int lan743x_otp_wait_till_not_busy(struct lan743x_adapter *adapter)
 {
 	unsigned long timeout;
-	u32 buf;
+	u32 reg_val;
+
+	timeout = jiffies + HZ;
+	do {
+		if (time_after(jiffies, timeout)) {
+			netif_warn(adapter, drv, adapter->netdev,
+				   "Timeout on OTP_STATUS completion\n");
+			return -EIO;
+		}
+		udelay(1);
+		reg_val = lan743x_csr_read(adapter, OTP_STATUS);
+	} while (reg_val & OTP_STATUS_BUSY_);
+
+	return 0;
+}
+
+static int lan743x_otp_read(struct lan743x_adapter *adapter, u32 offset,
+			    u32 length, u8 *data)
+{
+	int ret;
 	int i;
 
-	buf = lan743x_csr_read(adapter, OTP_PWR_DN);
+	if (offset + length > MAX_OTP_SIZE)
+		return -EINVAL;
 
-	if (buf & OTP_PWR_DN_PWRDN_N_) {
-		/* clear it and wait to be cleared */
-		lan743x_csr_write(adapter, OTP_PWR_DN, 0);
-
-		timeout = jiffies + HZ;
-		do {
-			udelay(1);
-			buf = lan743x_csr_read(adapter, OTP_PWR_DN);
-			if (time_after(jiffies, timeout)) {
-				netif_warn(adapter, drv, adapter->netdev,
-					   "timeout on OTP_PWR_DN completion\n");
-				return -EIO;
-			}
-		} while (buf & OTP_PWR_DN_PWRDN_N_);
+	ret = lan743x_otp_power_up(adapter);
+	if (ret < 0)
+		return ret;
+
+	ret = lan743x_otp_wait_till_not_busy(adapter);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < length; i++) {
+		lan743x_otp_set_address(adapter, offset + i);
+
+		lan743x_otp_read_go(adapter);
+		ret = lan743x_otp_wait_till_not_busy(adapter);
+		if (ret < 0)
+			return ret;
+		data[i] = lan743x_csr_read(adapter, OTP_READ_DATA);
 	}
 
+	lan743x_otp_power_down(adapter);
+
+	return 0;
+}
+
+static int lan743x_otp_write(struct lan743x_adapter *adapter, u32 offset,
+			     u32 length, u8 *data)
+{
+	int ret;
+	int i;
+
+	if (offset + length > MAX_OTP_SIZE)
+		return -EINVAL;
+
+	ret = lan743x_otp_power_up(adapter);
+	if (ret < 0)
+		return ret;
+
+	ret = lan743x_otp_wait_till_not_busy(adapter);
+	if (ret < 0)
+		return ret;
+
 	/* set to BYTE program mode */
 	lan743x_csr_write(adapter, OTP_PRGM_MODE, OTP_PRGM_MODE_BYTE_);
 
 	for (i = 0; i < length; i++) {
-		lan743x_csr_write(adapter, OTP_ADDR1,
-				  ((offset + i) >> 8) &
-				  OTP_ADDR1_15_11_MASK_);
-		lan743x_csr_write(adapter, OTP_ADDR2,
-				  ((offset + i) &
-				  OTP_ADDR2_10_3_MASK_));
+		lan743x_otp_set_address(adapter, offset + i);
+
 		lan743x_csr_write(adapter, OTP_PRGM_DATA, data[i]);
 		lan743x_csr_write(adapter, OTP_TST_CMD, OTP_TST_CMD_PRGVRFY_);
 		lan743x_csr_write(adapter, OTP_CMD_GO, OTP_CMD_GO_GO_);
 
-		timeout = jiffies + HZ;
-		do {
-			udelay(1);
-			buf = lan743x_csr_read(adapter, OTP_STATUS);
-			if (time_after(jiffies, timeout)) {
-				netif_warn(adapter, drv, adapter->netdev,
-					   "Timeout on OTP_STATUS completion\n");
-				return -EIO;
-			}
-		} while (buf & OTP_STATUS_BUSY_);
+		ret = lan743x_otp_wait_till_not_busy(adapter);
+		if (ret < 0)
+			return ret;
 	}
 
+	lan743x_otp_power_down(adapter);
+
 	return 0;
 }
 
@@ -120,6 +197,9 @@ static int lan743x_eeprom_read(struct lan743x_adapter *adapter,
 	u32 val;
 	int i;
 
+	if (offset + length > MAX_EEPROM_SIZE)
+		return -EINVAL;
+
 	retval = lan743x_eeprom_confirm_not_busy(adapter);
 	if (retval)
 		return retval;
@@ -148,6 +228,9 @@ static int lan743x_eeprom_write(struct lan743x_adapter *adapter,
 	u32 val;
 	int i;
 
+	if (offset + length > MAX_EEPROM_SIZE)
+		return -EINVAL;
+
 	retval = lan743x_eeprom_confirm_not_busy(adapter);
 	if (retval)
 		return retval;
@@ -207,6 +290,11 @@ static void lan743x_ethtool_set_msglevel(struct net_device *netdev,
 
 static int lan743x_ethtool_get_eeprom_len(struct net_device *netdev)
 {
+	struct lan743x_adapter *adapter = netdev_priv(netdev);
+
+	if (adapter->flags & LAN743X_ADAPTER_FLAG_OTP)
+		return MAX_OTP_SIZE;
+
 	return MAX_EEPROM_SIZE;
 }
 
@@ -214,8 +302,14 @@ static int lan743x_ethtool_get_eeprom(struct net_device *netdev,
 				      struct ethtool_eeprom *ee, u8 *data)
 {
 	struct lan743x_adapter *adapter = netdev_priv(netdev);
+	int ret = 0;
+
+	if (adapter->flags & LAN743X_ADAPTER_FLAG_OTP)
+		ret = lan743x_otp_read(adapter, ee->offset, ee->len, data);
+	else
+		ret = lan743x_eeprom_read(adapter, ee->offset, ee->len, data);
 
-	return lan743x_eeprom_read(adapter, ee->offset, ee->len, data);
+	return ret;
 }
 
 static int lan743x_ethtool_set_eeprom(struct net_device *netdev,
@@ -224,17 +318,18 @@ static int lan743x_ethtool_set_eeprom(struct net_device *netdev,
 	struct lan743x_adapter *adapter = netdev_priv(netdev);
 	int ret = -EINVAL;
 
-	if (ee->magic == LAN743X_EEPROM_MAGIC)
-		ret = lan743x_eeprom_write(adapter, ee->offset, ee->len,
-					   data);
-	/* Beware!  OTP is One Time Programming ONLY!
-	 * So do some strict condition check before messing up
-	 */
-	else if ((ee->magic == LAN743X_OTP_MAGIC) &&
-		 (ee->offset == 0) &&
-		 (ee->len == MAX_EEPROM_SIZE) &&
-		 (data[0] == OTP_INDICATOR_1))
-		ret = lan743x_otp_write(adapter, ee->offset, ee->len, data);
+	if (adapter->flags & LAN743X_ADAPTER_FLAG_OTP) {
+		/* Beware!  OTP is One Time Programming ONLY! */
+		if (ee->magic == LAN743X_OTP_MAGIC) {
+			ret = lan743x_otp_write(adapter, ee->offset,
+						ee->len, data);
+		}
+	} else {
+		if (ee->magic == LAN743X_EEPROM_MAGIC) {
+			ret = lan743x_eeprom_write(adapter, ee->offset,
+						   ee->len, data);
+		}
+	}
 
 	return ret;
 }
@@ -360,6 +455,10 @@ static const u32 lan743x_set2_hw_cnt_addr[] = {
 	STAT_TX_COUNTER_ROLLOVER_STATUS
 };
 
+static const char lan743x_priv_flags_strings[][ETH_GSTRING_LEN] = {
+	"OTP_ACCESS",
+};
+
 static void lan743x_ethtool_get_strings(struct net_device *netdev,
 					u32 stringset, u8 *data)
 {
@@ -375,6 +474,10 @@ static void lan743x_ethtool_get_strings(struct net_device *netdev,
 		       lan743x_set2_hw_cnt_strings,
 		       sizeof(lan743x_set2_hw_cnt_strings));
 		break;
+	case ETH_SS_PRIV_FLAGS:
+		memcpy(data, lan743x_priv_flags_strings,
+		       sizeof(lan743x_priv_flags_strings));
+		break;
 	}
 }
 
@@ -399,6 +502,22 @@ static void lan743x_ethtool_get_ethtool_stats(struct net_device *netdev,
 	}
 }
 
+static u32 lan743x_ethtool_get_priv_flags(struct net_device *netdev)
+{
+	struct lan743x_adapter *adapter = netdev_priv(netdev);
+
+	return adapter->flags;
+}
+
+static int lan743x_ethtool_set_priv_flags(struct net_device *netdev, u32 flags)
+{
+	struct lan743x_adapter *adapter = netdev_priv(netdev);
+
+	adapter->flags = flags;
+
+	return 0;
+}
+
 static int lan743x_ethtool_get_sset_count(struct net_device *netdev, int sset)
 {
 	switch (sset) {
@@ -411,6 +530,8 @@ static int lan743x_ethtool_get_sset_count(struct net_device *netdev, int sset)
 		ret += ARRAY_SIZE(lan743x_set2_hw_cnt_strings);
 		return ret;
 	}
+	case ETH_SS_PRIV_FLAGS:
+		return ARRAY_SIZE(lan743x_priv_flags_strings);
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -705,6 +826,8 @@ const struct ethtool_ops lan743x_ethtool_ops = {
 	.set_eeprom = lan743x_ethtool_set_eeprom,
 	.get_strings = lan743x_ethtool_get_strings,
 	.get_ethtool_stats = lan743x_ethtool_get_ethtool_stats,
+	.get_priv_flags = lan743x_ethtool_get_priv_flags,
+	.set_priv_flags = lan743x_ethtool_set_priv_flags,
 	.get_sset_count = lan743x_ethtool_get_sset_count,
 	.get_rxnfc = lan743x_ethtool_get_rxnfc,
 	.get_rxfh_key_size = lan743x_ethtool_get_rxfh_key_size,