net: ethernet: oa_tc6: implement software reset

Reset complete bit is set when the MAC-PHY reset completes and ready for
configuration. Additionally reset complete bit in the STS0 register has
to be written by one upon reset complete to clear the interrupt.
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Parthiban Veerasooran <Parthiban.Veerasooran@microchip.com>
Link: https://patch.msgid.link/20240909082514.262942-5-Parthiban.Veerasooran@microchip.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/oa_tc6.c

@@ -6,8 +6,18 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/iopoll.h>
 #include <linux/oa_tc6.h>
 
+/* OPEN Alliance TC6 registers */
+/* Reset Control and Status Register */
+#define OA_TC6_REG_RESET			0x0003
+#define RESET_SWRESET				BIT(0)	/* Software Reset */
+
+/* Status Register #0 */
+#define OA_TC6_REG_STATUS0			0x0008
+#define STATUS0_RESETC				BIT(6)	/* Reset Complete */
+
 /* Control command header */
 #define OA_TC6_CTRL_HEADER_DATA_NOT_CTRL	BIT(31)
 #define OA_TC6_CTRL_HEADER_WRITE_NOT_READ	BIT(29)
@@ -24,6 +34,8 @@
 						(OA_TC6_CTRL_MAX_REGISTERS *\
 						OA_TC6_CTRL_REG_VALUE_SIZE) +\
 						OA_TC6_CTRL_IGNORED_SIZE)
+#define STATUS0_RESETC_POLL_DELAY		1000
+#define STATUS0_RESETC_POLL_TIMEOUT		1000000
 
 /* Internal structure for MAC-PHY drivers */
 struct oa_tc6 {
@@ -279,6 +291,42 @@ int oa_tc6_write_register(struct oa_tc6 *tc6, u32 address, u32 value)
 }
 EXPORT_SYMBOL_GPL(oa_tc6_write_register);
 
+static int oa_tc6_read_status0(struct oa_tc6 *tc6)
+{
+	u32 regval;
+	int ret;
+
+	ret = oa_tc6_read_register(tc6, OA_TC6_REG_STATUS0, &regval);
+	if (ret) {
+		dev_err(&tc6->spi->dev, "STATUS0 register read failed: %d\n",
+			ret);
+		return 0;
+	}
+
+	return regval;
+}
+
+static int oa_tc6_sw_reset_macphy(struct oa_tc6 *tc6)
+{
+	u32 regval = RESET_SWRESET;
+	int ret;
+
+	ret = oa_tc6_write_register(tc6, OA_TC6_REG_RESET, regval);
+	if (ret)
+		return ret;
+
+	/* Poll for soft reset complete for every 1ms until 1s timeout */
+	ret = readx_poll_timeout(oa_tc6_read_status0, tc6, regval,
+				 regval & STATUS0_RESETC,
+				 STATUS0_RESETC_POLL_DELAY,
+				 STATUS0_RESETC_POLL_TIMEOUT);
+	if (ret)
+		return -ENODEV;
+
+	/* Clear the reset complete status */
+	return oa_tc6_write_register(tc6, OA_TC6_REG_STATUS0, regval);
+}
+
 /**
  * oa_tc6_init - allocates and initializes oa_tc6 structure.
  * @spi: device with which data will be exchanged.
@@ -289,6 +337,7 @@ EXPORT_SYMBOL_GPL(oa_tc6_write_register);
 struct oa_tc6 *oa_tc6_init(struct spi_device *spi)
 {
 	struct oa_tc6 *tc6;
+	int ret;
 
 	tc6 = devm_kzalloc(&spi->dev, sizeof(*tc6), GFP_KERNEL);
 	if (!tc6)
@@ -313,6 +362,13 @@ struct oa_tc6 *oa_tc6_init(struct spi_device *spi)
 	if (!tc6->spi_ctrl_rx_buf)
 		return NULL;
 
+	ret = oa_tc6_sw_reset_macphy(tc6);
+	if (ret) {
+		dev_err(&tc6->spi->dev,
+			"MAC-PHY software reset failed: %d\n", ret);
+		return NULL;
+	}
+
 	return tc6;
 }
 EXPORT_SYMBOL_GPL(oa_tc6_init);