[PATCH net-next v2 3/9] net: ethernet: oa_tc6: implement OA TC6 configuration function

[Parthiban Veerasooran]

Read STDCAP register for the MAC-PHY capability and check against the
configuration parameters such as chunk payload, tx cut through and rx cut
through to configure the MAC-PHY. It also configures the control command
protected/unprotected mode.

In cut through mode configuration the MAC-PHY doesn't buffer the incoming
data. In tx case, it passes the data to the network if the configured cps
of data available. In rx case, it passes the data to the SPI host if the
configured cps of data available from the network. Also disables all the
errors mask in the IMASK0 register to check for the errors.

Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@xxxxxxxxxxxxx>
---
 drivers/net/ethernet/oa_tc6.c | 86 ++++++++++++++++++++++++++++++++++-
 include/linux/oa_tc6.h        | 24 +++++++++-
 2 files changed, 107 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/oa_tc6.c b/drivers/net/ethernet/oa_tc6.c
index e4457569135f..9a98d59f286d 100644
--- a/drivers/net/ethernet/oa_tc6.c
+++ b/drivers/net/ethernet/oa_tc6.c
@@ -8,6 +8,7 @@
 #include <linux/bitfield.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
+#include <linux/of.h>
 #include <linux/oa_tc6.h>
 
 /* Opaque structure for MACPHY drivers */
@@ -16,6 +17,7 @@ struct oa_tc6 {
 	u8 *ctrl_tx_buf;
 	u8 *ctrl_rx_buf;
 	bool prote;
+	u32 cps;
 };
 
 static int oa_tc6_spi_transfer(struct spi_device *spi, u8 *ptx, u8 *prx, u16 len)
@@ -198,6 +200,81 @@ static int oa_tc6_perform_ctrl(struct oa_tc6 *tc6, u32 addr, u32 val[], u8 len,
 	return ret;
 }
 
+static int oa_tc6_configure(struct oa_tc6 *tc6)
+{
+	struct spi_device *spi = tc6->spi;
+	struct device_node *oa_node;
+	u32 regval;
+	u8 mincps;
+	bool ctc;
+	int ret;
+
+	/* Read and configure the IMASK0 register for unmasking the interrupts */
+	ret = oa_tc6_perform_ctrl(tc6, IMASK0, &regval, 1, false, false);
+	if (ret)
+		return ret;
+
+	regval &= ~(TXPEM & TXBOEM & TXBUEM & RXBOEM & LOFEM & HDREM);
+
+	ret = oa_tc6_perform_ctrl(tc6, IMASK0, &regval, 1, true, false);
+	if (ret)
+		return ret;
+
+	/* Read STDCAP register to get the MAC-PHY standard capabilities */
+	ret = oa_tc6_perform_ctrl(tc6, STDCAP, &regval, 1, false, false);
+	if (ret)
+		return ret;
+
+	mincps = FIELD_GET(MINCPS, regval);
+	ctc = (regval & CTC) ? true : false;
+
+	regval = 0;
+	oa_node = of_get_child_by_name(spi->dev.of_node, "oa-tc6");
+	if (oa_node) {
+		/* Read OA parameters from DT */
+		if (of_property_present(oa_node, "oa-cps")) {
+			ret = of_property_read_u32(oa_node, "oa-cps", &tc6->cps);
+			if (ret < 0)
+				return ret;
+			/* Return error if the configured cps is less than the
+			 * minimum cps supported by the MAC-PHY.
+			 */
+			if (tc6->cps < mincps)
+				return -ENODEV;
+		} else {
+			tc6->cps = 64;
+		}
+		if (of_property_present(oa_node, "oa-txcte")) {
+			/* Return error if the tx cut through mode is configured
+			 * but it is not supported by MAC-PHY.
+			 */
+			if (ctc)
+				regval |= TXCTE;
+			else
+				return -ENODEV;
+		}
+		if (of_property_present(oa_node, "oa-rxcte")) {
+			/* Return error if the rx cut through mode is configured
+			 * but it is not supported by MAC-PHY.
+			 */
+			if (ctc)
+				regval |= RXCTE;
+			else
+				return -ENODEV;
+		}
+		if (of_property_present(oa_node, "oa-prote")) {
+			regval |= PROTE;
+			tc6->prote = true;
+		}
+	} else {
+		tc6->cps = 64;
+	}
+
+	regval |= FIELD_PREP(CPS, ilog2(tc6->cps) / ilog2(2)) | SYNC;
+
+	return oa_tc6_perform_ctrl(tc6, CONFIG0, &regval, 1, true, false);
+}
+
 static int oa_tc6_sw_reset(struct oa_tc6 *tc6)
 {
 	u32 regval;
@@ -310,7 +387,7 @@ EXPORT_SYMBOL_GPL(oa_tc6_read_registers);
  * Returns pointer reference to the oa_tc6 structure if all the memory
  * allocation success otherwise NULL.
  */
-struct oa_tc6 *oa_tc6_init(struct spi_device *spi, bool prote)
+struct oa_tc6 *oa_tc6_init(struct spi_device *spi)
 {
 	struct oa_tc6 *tc6;
 
@@ -327,7 +404,6 @@ struct oa_tc6 *oa_tc6_init(struct spi_device *spi, bool prote)
 		return NULL;
 
 	tc6->spi = spi;
-	tc6->prote = prote;
 
 	/* Perform MAC-PHY software reset */
 	if (oa_tc6_sw_reset(tc6)) {
@@ -335,6 +411,12 @@ struct oa_tc6 *oa_tc6_init(struct spi_device *spi, bool prote)
 		return NULL;
 	}
 
+	/* Perform OA parameters and MAC-PHY configuration */
+	if (oa_tc6_configure(tc6)) {
+		dev_err(&spi->dev, "OA and MAC-PHY configuration failed\n");
+		return NULL;
+	}
+
 	return tc6;
 }
 EXPORT_SYMBOL_GPL(oa_tc6_init);
diff --git a/include/linux/oa_tc6.h b/include/linux/oa_tc6.h
index 8a838499da97..378636fd9ca8 100644
--- a/include/linux/oa_tc6.h
+++ b/include/linux/oa_tc6.h
@@ -22,15 +22,37 @@
 #define TC6_CTRL_BUF_SIZE	1032	/* Max ctrl buffer size for 128 regs */
 
 /* Open Alliance TC6 Standard Control and Status Registers */
+/* Standard Capabilities Register */
+#define STDCAP			0x0002
+#define CTC			BIT(7)	/* Cut-Through Capability */
+#define MINCPS			GENMASK(2, 0)	/* Minimum supported cps */
+
 /* Reset Control and Status Register */
 #define RESET			0x0003
 #define SWRESET			BIT(0)	/* Software Reset */
 
+/* Configuration Register #0 */
+#define CONFIG0			0x0004
+#define SYNC			BIT(15)	/* Configuration Synchronization */
+#define TXCTE			BIT(9)	/* Tx cut-through enable */
+#define RXCTE			BIT(8)	/* Rx cut-through enable */
+#define PROTE			BIT(5)	/* Ctrl read/write Protection Enable */
+#define CPS			GENMASK(2, 0)	/* Chunk Payload Size */
+
 /* Status Register #0 */
 #define STATUS0			0x0008
 #define RESETC			BIT(6)	/* Reset Complete */
 
-struct oa_tc6 *oa_tc6_init(struct spi_device *spi, bool prote);
+/* Interrupt Mask Register #0 */
+#define IMASK0			0x000C
+#define HDREM			BIT(5)	/* Header Error Mask */
+#define LOFEM			BIT(4)	/* Loss of Framing Error Mask */
+#define RXBOEM			BIT(3)	/* Rx Buffer Overflow Error Mask */
+#define TXBUEM			BIT(2)	/* Tx Buffer Underflow Error Mask */
+#define TXBOEM			BIT(1)	/* Tx Buffer Overflow Error Mask */
+#define TXPEM			BIT(0)	/* Tx Protocol Error Mask */
+
+struct oa_tc6 *oa_tc6_init(struct spi_device *spi);
 int oa_tc6_write_register(struct oa_tc6 *tc6, u32 addr, u32 val);
 int oa_tc6_read_register(struct oa_tc6 *tc6, u32 addr, u32 *val);
 int oa_tc6_write_registers(struct oa_tc6 *tc6, u32 addr, u32 val[], u8 len);
-- 
2.34.1