diff mbox series

[v2,2/7] serial: exar: add support for reading from Exar EEPROM

Message ID d16cb88f916914278e125023c856bbf85d0908c1.1712863999.git.pnewman@connecttech.com
State New
Headers show
Series serial: exar: add Connect Tech serial cards to Exar driver | expand

Commit Message

Parker Newman April 11, 2024, 8:25 p.m. UTC 
From: Parker Newman <pnewman@connecttech.com>

- Adds support for reading a word from the Exar EEPROM.
- Adds exar_write_reg/exar_read_reg for reading and writing to the UART's
config registers.

Signed-off-by: Parker Newman <pnewman@connecttech.com>
---
 drivers/tty/serial/8250/8250_exar.c | 110 ++++++++++++++++++++++++++++
 1 file changed, 110 insertions(+)

--
2.43.2

Comments

Ilpo Järvinen April 12, 2024, 10:36 a.m. UTC | #1 
On Thu, 11 Apr 2024, parker@finest.io wrote:

> From: Parker Newman <pnewman@connecttech.com>
> 
> - Adds support for reading a word from the Exar EEPROM.
> - Adds exar_write_reg/exar_read_reg for reading and writing to the UART's
> config registers.
> 
> Signed-off-by: Parker Newman <pnewman@connecttech.com>
> ---
>  drivers/tty/serial/8250/8250_exar.c | 110 ++++++++++++++++++++++++++++
>  1 file changed, 110 insertions(+)
> 
> diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
> index 4d1e07343d0b..49d690344e65 100644
> --- a/drivers/tty/serial/8250/8250_exar.c
> +++ b/drivers/tty/serial/8250/8250_exar.c
> @@ -128,6 +128,16 @@
>  #define UART_EXAR_DLD			0x02 /* Divisor Fractional */
>  #define UART_EXAR_DLD_485_POLARITY	0x80 /* RS-485 Enable Signal Polarity */
> 
> +/* EEPROM registers */
> +#define UART_EXAR_REGB                  0x8e
> +#define UART_EXAR_REGB_EECK             BIT(4)
> +#define UART_EXAR_REGB_EECS             BIT(5)
> +#define UART_EXAR_REGB_EEDI             BIT(6)
> +#define UART_EXAR_REGB_EEDO             BIT(7)
> +#define UART_EXAR_REGB_EE_ADDR_SIZE     6
> +#define UART_EXAR_REGB_EE_DATA_SIZE     16
> +
> +

Extra new line.

>  /*
>   * IOT2040 MPIO wiring semantics:
>   *
> @@ -195,6 +205,106 @@ struct exar8250 {
>  	int			line[];
>  };
> 
> +static inline void exar_write_reg(struct exar8250 *priv,
> +				unsigned int reg, uint8_t value)
> +{
> +	if (!priv || !priv->virt)
> +		return;
> +
> +	writeb(value, priv->virt + reg);
> +}
> +
> +static inline uint8_t exar_read_reg(struct exar8250 *priv, unsigned int reg)
> +{
> +	if (!priv || !priv->virt)
> +		return 0;
> +
> +	return readb(priv->virt + reg);
> +}
> +
> +static inline void exar_ee_select(struct exar8250 *priv, bool enable)
> +{
> +	uint8_t value = 0x00;
> +
> +	if (enable)
> +		value |= UART_EXAR_REGB_EECS;

You could just do:
	u8 value;

	value = enable ? UART_EXAR_REGB_EECS : 0;

Or even:

	exar_write_reg(priv, UART_EXAR_REGB, enable ? UART_EXAR_REGB_EECS : 0);
> +
> +	exar_write_reg(priv, UART_EXAR_REGB, value);
> +	udelay(2);
> +}
> +
> +static inline void exar_ee_write_bit(struct exar8250 *priv, int bit)
> +{
> +	uint8_t value = UART_EXAR_REGB_EECS;
> +
> +	if (bit)
> +		value |= UART_EXAR_REGB_EEDI;
> +
> +	//Clock out the bit on the i2c interface
> +	exar_write_reg(priv, UART_EXAR_REGB, value);
> +	udelay(2);
> +
> +	value |= UART_EXAR_REGB_EECK;
> +
> +	exar_write_reg(priv, UART_EXAR_REGB, value);
> +	udelay(2);
> +}
> +
> +static inline uint8_t exar_ee_read_bit(struct exar8250 *priv)
> +{
> +	uint8_t regb;
> +	uint8_t value = UART_EXAR_REGB_EECS;
> +
> +	//Clock in the bit on the i2c interface
> +	exar_write_reg(priv, UART_EXAR_REGB, value);
> +	udelay(2);
> +
> +	value |= UART_EXAR_REGB_EECK;
> +
> +	exar_write_reg(priv, UART_EXAR_REGB, value);
> +	udelay(2);
> +
> +	regb = exar_read_reg(priv, UART_EXAR_REGB);
> +
> +	return (regb & UART_EXAR_REGB_EEDO ? 1 : 0);
> +}
> +
> +/**
> + * exar_ee_read() - Read a word from the EEPROM
> + * @priv: Device's private structure
> + * @ee_addr: Offset of EEPROM to read word from
> + *
> + * Read a single 16bit word from an Exar UART's EEPROM

Add missing .

> + *
> + * Return: EEPROM word on success, negative error code on failure

This function does not return any -Exx code as far as I can see??

> + */
> +static int exar_ee_read(struct exar8250 *priv, uint8_t ee_addr)
> +{
> +	int i;
> +	int data = 0;
> +
> +	exar_ee_select(priv, true);
> +
> +	//Send read command (opcode 110)
> +	exar_ee_write_bit(priv, 1);
> +	exar_ee_write_bit(priv, 1);
> +	exar_ee_write_bit(priv, 0);
> +
> +	//Send address to read from
> +	for (i = 1 << (UART_EXAR_REGB_EE_ADDR_SIZE - 1); i; i >>= 1)
> +		exar_ee_write_bit(priv, (ee_addr & i));
> +
> +	//Read data 1 bit at a time
> +	for (i = 0; i <= UART_EXAR_REGB_EE_DATA_SIZE; i++) {
> +		data <<= 1;
> +		data |= exar_ee_read_bit(priv);
> +	}
> +
> +	exar_ee_select(priv, false);
> +
> +	return data;
> +}
diff mbox series

Patch

diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 4d1e07343d0b..49d690344e65 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -128,6 +128,16 @@ 
 #define UART_EXAR_DLD			0x02 /* Divisor Fractional */
 #define UART_EXAR_DLD_485_POLARITY	0x80 /* RS-485 Enable Signal Polarity */

+/* EEPROM registers */
+#define UART_EXAR_REGB                  0x8e
+#define UART_EXAR_REGB_EECK             BIT(4)
+#define UART_EXAR_REGB_EECS             BIT(5)
+#define UART_EXAR_REGB_EEDI             BIT(6)
+#define UART_EXAR_REGB_EEDO             BIT(7)
+#define UART_EXAR_REGB_EE_ADDR_SIZE     6
+#define UART_EXAR_REGB_EE_DATA_SIZE     16
+
+
 /*
  * IOT2040 MPIO wiring semantics:
  *
@@ -195,6 +205,106 @@  struct exar8250 {
 	int			line[];
 };

+static inline void exar_write_reg(struct exar8250 *priv,
+				unsigned int reg, uint8_t value)
+{
+	if (!priv || !priv->virt)
+		return;
+
+	writeb(value, priv->virt + reg);
+}
+
+static inline uint8_t exar_read_reg(struct exar8250 *priv, unsigned int reg)
+{
+	if (!priv || !priv->virt)
+		return 0;
+
+	return readb(priv->virt + reg);
+}
+
+static inline void exar_ee_select(struct exar8250 *priv, bool enable)
+{
+	uint8_t value = 0x00;
+
+	if (enable)
+		value |= UART_EXAR_REGB_EECS;
+
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+}
+
+static inline void exar_ee_write_bit(struct exar8250 *priv, int bit)
+{
+	uint8_t value = UART_EXAR_REGB_EECS;
+
+	if (bit)
+		value |= UART_EXAR_REGB_EEDI;
+
+	//Clock out the bit on the i2c interface
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+
+	value |= UART_EXAR_REGB_EECK;
+
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+}
+
+static inline uint8_t exar_ee_read_bit(struct exar8250 *priv)
+{
+	uint8_t regb;
+	uint8_t value = UART_EXAR_REGB_EECS;
+
+	//Clock in the bit on the i2c interface
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+
+	value |= UART_EXAR_REGB_EECK;
+
+	exar_write_reg(priv, UART_EXAR_REGB, value);
+	udelay(2);
+
+	regb = exar_read_reg(priv, UART_EXAR_REGB);
+
+	return (regb & UART_EXAR_REGB_EEDO ? 1 : 0);
+}
+
+/**
+ * exar_ee_read() - Read a word from the EEPROM
+ * @priv: Device's private structure
+ * @ee_addr: Offset of EEPROM to read word from
+ *
+ * Read a single 16bit word from an Exar UART's EEPROM
+ *
+ * Return: EEPROM word on success, negative error code on failure
+ */
+static int exar_ee_read(struct exar8250 *priv, uint8_t ee_addr)
+{
+	int i;
+	int data = 0;
+
+	exar_ee_select(priv, true);
+
+	//Send read command (opcode 110)
+	exar_ee_write_bit(priv, 1);
+	exar_ee_write_bit(priv, 1);
+	exar_ee_write_bit(priv, 0);
+
+	//Send address to read from
+	for (i = 1 << (UART_EXAR_REGB_EE_ADDR_SIZE - 1); i; i >>= 1)
+		exar_ee_write_bit(priv, (ee_addr & i));
+
+	//Read data 1 bit at a time
+	for (i = 0; i <= UART_EXAR_REGB_EE_DATA_SIZE; i++) {
+		data <<= 1;
+		data |= exar_ee_read_bit(priv);
+	}
+
+	exar_ee_select(priv, false);
+
+	return data;
+}
+
 static void exar_pm(struct uart_port *port, unsigned int state, unsigned int old)
 {
 	/*