[PATCH v1 4/6] serial: 8250_exar: Replace custom EEPROM read with eeprom_93cx6

[Parker Newman <parker@finest.io>]

From: Parker Newman <pnewman@connecttech.com>

Replace the custom 93cx6 EEPROM read functions with the eeprom_93cx6
driver. This removes duplicate code and improves code readability.

exar_ee_read() calls are replaced with eeprom_93cx6_read() or
eeprom_93cx6_multiread().

Link to discussion with Andy Shevchenko:
Link: https://lore.kernel.org/linux-serial/Ztr5u2wEt8VF1IdI@black.fi.intel.com/

Note: Old exar_ee_read() and associated functions are removed in next
patch in this series.

Signed-off-by: Parker Newman <pnewman@connecttech.com>
---
 drivers/tty/serial/8250/8250_exar.c | 54 +++++++++++++++++++++++------
 1 file changed, 43 insertions(+), 11 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index b7a75db15249..0edb5aeba199 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -21,6 +21,7 @@
 #include <linux/property.h>
 #include <linux/string.h>
 #include <linux/types.h>
+#include <linux/eeprom_93cx6.h>

 #include <linux/serial_8250.h>
 #include <linux/serial_core.h>
@@ -252,6 +253,7 @@ struct exar8250 {
 	unsigned int		nr;
 	unsigned int		osc_freq;
 	struct exar8250_board	*board;
+	struct eeprom_93cx6	eeprom;
 	void __iomem		*virt;
 	int			line[];
 };
@@ -355,6 +357,39 @@ static u16 exar_ee_read(struct exar8250 *priv, u8 ee_addr)
 	return data;
 }

+static void exar_eeprom_93cx6_reg_read(struct eeprom_93cx6 *eeprom)
+{
+	struct exar8250 *priv = (struct exar8250 *)eeprom->data;
+	u8 regb = exar_read_reg(priv, UART_EXAR_REGB);
+
+	// EECK and EECS always read 0 from REGB so only set EEDO
+	eeprom->reg_data_out = regb & UART_EXAR_REGB_EEDO;
+}
+
+static void exar_eeprom_93cx6_reg_write(struct eeprom_93cx6 *eeprom)
+{
+	struct exar8250 *priv = (struct exar8250 *)eeprom->data;
+	u8 regb = 0;
+
+	if (eeprom->reg_data_in)
+		regb |= UART_EXAR_REGB_EEDI;
+	if (eeprom->reg_data_clock)
+		regb |= UART_EXAR_REGB_EECK;
+	if (eeprom->reg_chip_select)
+		regb |= UART_EXAR_REGB_EECS;
+
+	exar_write_reg(priv, UART_EXAR_REGB, regb);
+}
+
+static void exar_eeprom_init(struct exar8250 *priv)
+{
+	priv->eeprom.data = (void *)priv;
+	priv->eeprom.register_read = exar_eeprom_93cx6_reg_read;
+	priv->eeprom.register_write = exar_eeprom_93cx6_reg_write;
+	priv->eeprom.width = PCI_EEPROM_WIDTH_93C46;
+	priv->eeprom.quirks |= PCI_EEPROM_QUIRK_EXTRA_READ_CYCLE;
+}
+
 /**
  * exar_mpio_config_output() - Configure an Exar MPIO as an output
  * @priv: Device's private structure
@@ -696,20 +731,15 @@ static int cti_plx_int_enable(struct exar8250 *priv)
  */
 static int cti_read_osc_freq(struct exar8250 *priv, u8 eeprom_offset)
 {
-	u16 lower_word;
-	u16 upper_word;
+	__le32 osc_freq_le;

-	lower_word = exar_ee_read(priv, eeprom_offset);
-	// Check if EEPROM word was blank
-	if (lower_word == 0xFFFF)
-		return -EIO;
+	eeprom_93cx6_multiread(&priv->eeprom, eeprom_offset,
+				(__le16 *)&osc_freq_le, 2);

-	upper_word = exar_ee_read(priv, (eeprom_offset + 1));
-	if (upper_word == 0xFFFF)
+	if (osc_freq_le == 0xFFFFFFFF)
 		return -EIO;

-	return FIELD_PREP(CTI_EE_MASK_OSC_FREQ_LOWER, lower_word) |
-	       FIELD_PREP(CTI_EE_MASK_OSC_FREQ_UPPER, upper_word);
+	return le32_to_cpu(osc_freq_le);
 }

 /**
@@ -833,7 +863,7 @@ static enum cti_port_type cti_get_port_type_xr17v35x(struct exar8250 *priv,
 	u8 offset;

 	offset = CTI_EE_OFF_XR17V35X_PORT_FLAGS + port_num;
-	port_flags = exar_ee_read(priv, offset);
+	eeprom_93cx6_read(&priv->eeprom, offset, &port_flags);

 	port_type = FIELD_GET(CTI_EE_MASK_PORT_FLAGS_TYPE, port_flags);
 	if (CTI_PORT_TYPE_VALID(port_type))
@@ -1551,6 +1581,8 @@ exar_pci_probe(struct pci_dev *pcidev, const struct pci_device_id *ent)
 	if (rc)
 		return rc;

+	exar_eeprom_init(priv);
+
 	for (i = 0; i < nr_ports && i < maxnr; i++) {
 		rc = board->setup(priv, pcidev, &uart, i);
 		if (rc) {
--
2.46.0