From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
With this driver, it is very hard to debug the registers using
the /sys/kernel/debug/regmap interface.
The main reason is that bits 0 and 1 of the register address
correspond to the channels bits, so the register address itself starts
at bit 2, so we must 'mentally' shift each register address by 2 bits
to get its offset.
Also, only channels 0 and 1 are supported, so combinations of bits
0 and 1 being 10b and 11b are invalid, and the display of these
registers is useless.
For example:
cat /sys/kernel/debug/regmap/spi0.0/registers
04: 10 -> Port 0, register offset 1
05: 10 -> Port 1, register offset 1
06: 00 -> Port 2, register offset 1 -> invalid
07: 00 -> port 3, register offset 1 -> invalid
...
Add a debug module parameter to call a custom dump function for each
port registers after the probe phase to help debug.
Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
---
drivers/tty/serial/sc16is7xx.c | 30 ++++++++++++++++++++++++++++++
1 file changed, 30 insertions(+)
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 03d00b144304..693b6cc371f8 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -347,6 +347,10 @@ struct sc16is7xx_port {
struct sc16is7xx_one p[];
};
+static bool debug;
+module_param(debug, bool, 0644);
+MODULE_PARM_DESC(debug, "enable/disable debug messages");
+
static unsigned long sc16is7xx_lines;
static struct uart_driver sc16is7xx_uart = {
@@ -387,6 +391,28 @@ static void sc16is7xx_port_write(struct uart_port *port, u8 reg, u8 val)
regmap_write(s->regmap, (reg << SC16IS7XX_REG_SHIFT) | line, val);
}
+static int sc16is7xx_port_dump(struct uart_port *port)
+{
+ int i;
+ unsigned char *buf;
+ char name[64];
+ const int regs_count_per_port = 16;
+
+ buf = devm_kzalloc(port->dev, regs_count_per_port, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ for (i = 0; i < regs_count_per_port; i++)
+ buf[i] = sc16is7xx_port_read(port, i);
+
+ snprintf(name, sizeof(name), "sc16is7xx %s%i: dump ",
+ sc16is7xx_uart.dev_name, port->line);
+ print_hex_dump(KERN_ERR, name, DUMP_PREFIX_OFFSET, 16, 1,
+ &((u8 *)buf)[0], regs_count_per_port, 1);
+
+ return 0;
+}
+
static void sc16is7xx_fifo_read(struct uart_port *port, unsigned int rxlen)
{
struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
@@ -1614,6 +1640,10 @@ static int sc16is7xx_probe(struct device *dev,
}
#endif
+ if (debug)
+ for (i = 0; i < devtype->nr_uart; ++i)
+ sc16is7xx_port_dump(&s->p[i].port);
+
/*
* Setup interrupt. We first try to acquire the IRQ line as level IRQ.
* If that succeeds, we can allow sharing the interrupt as well.
--
2.30.2
