From: parker@finest.io
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jirislaby@kernel.org>,
linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org
Cc: Parker Newman <pnewman@connecttech.com>
Subject: [PATCH v2 2/7] serial: exar: add support for reading from Exar EEPROM
Date: Thu, 11 Apr 2024 16:25:40 -0400 [thread overview]
Message-ID: <d16cb88f916914278e125023c856bbf85d0908c1.1712863999.git.pnewman@connecttech.com> (raw)
In-Reply-To: <cover.1712863999.git.pnewman@connecttech.com>
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
+
+
/*
* 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)
{
/*
--
2.43.2
next prev parent reply other threads:[~2024-04-11 20:26 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-11 20:25 [PATCH v2 0/7] serial: exar: add Connect Tech serial cards to Exar driver parker
2024-04-11 20:25 ` [PATCH v2 1/7] serial: exar: adding missing CTI and Exar PCI ids parker
2024-04-11 20:25 ` parker [this message]
2024-04-12 5:26 ` [PATCH v2 2/7] serial: exar: add support for reading from Exar EEPROM Greg Kroah-Hartman
2024-04-12 12:58 ` Parker Newman
2024-04-12 10:36 ` Ilpo Järvinen
2024-04-12 13:06 ` Parker Newman
2024-04-11 20:25 ` [PATCH v2 3/7] serial: exar: add support for config/set single MPIO parker
2024-04-12 5:29 ` Greg Kroah-Hartman
2024-04-12 13:05 ` Parker Newman
2024-04-12 10:20 ` Ilpo Järvinen
2024-04-12 13:36 ` Parker Newman
2024-04-12 13:44 ` Ilpo Järvinen
2024-04-11 20:25 ` [PATCH v2 4/7] serial: exar: add optional board_setup function parker
2024-04-12 10:08 ` Ilpo Järvinen
2024-04-12 13:50 ` Parker Newman
2024-04-11 20:25 ` [PATCH v2 5/7] serial: exar: add some CTI helper functions parker
2024-04-12 10:48 ` Ilpo Järvinen
2024-04-12 13:57 ` Parker Newman
2024-04-12 14:09 ` Ilpo Järvinen
2024-04-11 20:25 ` [PATCH v2 6/7] serial: exar: add CTI board and port setup functions parker
2024-04-12 10:57 ` Ilpo Järvinen
2024-04-12 15:19 ` Parker Newman
2024-04-12 15:28 ` Greg Kroah-Hartman
2024-04-12 15:39 ` Parker Newman
2024-04-11 20:25 ` [PATCH v2 7/7] serial: exar: fix: fix crash during shutdown if setup fails parker
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