[PATCH RFT] tty: serial: fsl_lpuart: Add register dump

[Sherry Sun]

> Subject: [PATCH RFT] tty: serial: fsl_lpuart: Add register dump
> 
> Dumping the registers from userspace for debug purposes isn't trivial,
> because runtime PM can gate the required clocks and any read access to
> these registers would result in a lockup.
> 
> So implement a register dump via debugfs, which deals with the runtime PM.

No need, you can disable runtime pm from user space before dump the registers.
For example: echo on > /sys/bus/platform/devices/29860000.serial/power/control

Best Regards
Sherry
> 
> Signed-off-by: Stefan Wahren <wahrenst at gmx.net>
> ---
> 
> Hi, I only have access to a board (i.MX93) with 32 bit registers, so it would be
> great if someone could test it for 8 bit registers.
> 
> Thanks
> 
>  drivers/tty/serial/fsl_lpuart.c | 69 +++++++++++++++++++++++++++++++++
>  1 file changed, 69 insertions(+)
> 
> diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c index
> 1bd7ec9c81ea..7e4b3e59414a 100644
> --- a/drivers/tty/serial/fsl_lpuart.c
> +++ b/drivers/tty/serial/fsl_lpuart.c
> @@ -10,6 +10,7 @@
>  #include <linux/circ_buf.h>
>  #include <linux/clk.h>
>  #include <linux/console.h>
> +#include <linux/debugfs.h>
>  #include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/dmaengine.h>
> @@ -23,6 +24,7 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_runtime.h>
> +#include <linux/seq_file.h>
>  #include <linux/serial_core.h>
>  #include <linux/slab.h>
>  #include <linux/tty_flip.h>
> @@ -291,6 +293,8 @@ struct lpuart_port {
>  	bool			is_cs7; /* Set to true when character size is 7
> */
>  					/* and the parity is enabled
> 	*/
>  	bool			dma_idle_int;
> +
> +	struct dentry		*debugfs_dir;
>  };
> 
>  struct lpuart_soc_data {
> @@ -1031,6 +1035,7 @@ static void lpuart32_rxint(struct lpuart_port *sport)
>  	}
> 
>  out:
> +
>  	uart_unlock_and_check_sysrq(&sport->port);
> 
>  	tty_flip_buffer_push(port);
> @@ -2860,6 +2865,67 @@ static int lpuart_global_reset(struct lpuart_port
> *sport)
>  	return 0;
>  }
> 
> +#ifdef CONFIG_DEBUG_FS
> +
> +#define dump_register_hex(_seq, _reg, _sport) \ seq_printf((_seq),
> +"%-12s: 0x%02x\n", #_reg, readb((_sport)->port.membase + (_reg)))
> +
> +#define dump_register32_hex(_seq, _reg, _sport) \ seq_printf((_seq),
> +"%-12s: 0x%08x\n", #_reg, lpuart32_read(&(_sport)->port, _reg))
> +
> +static int regs_show(struct seq_file *s, void *p) {
> +	struct lpuart_port *sport = s->private;
> +
> +	pm_runtime_get_sync(sport->port.dev);
> +
> +	if (lpuart_is_32(sport)) {
> +		dump_register32_hex(s, UARTBAUD, sport);
> +		dump_register32_hex(s, UARTSTAT, sport);
> +		dump_register32_hex(s, UARTCTRL, sport);
> +		dump_register32_hex(s, UARTMATCH, sport);
> +		dump_register32_hex(s, UARTMODIR, sport);
> +		dump_register32_hex(s, UARTFIFO, sport);
> +		dump_register32_hex(s, UARTWATER, sport);
> +	} else {
> +		dump_register_hex(s, UARTBDH, sport);
> +		dump_register_hex(s, UARTBDL, sport);
> +		dump_register_hex(s, UARTCR1, sport);
> +		dump_register_hex(s, UARTCR2, sport);
> +		dump_register_hex(s, UARTSR1, sport);
> +		dump_register_hex(s, UARTCR3, sport);
> +		dump_register_hex(s, UARTDR, sport);
> +		dump_register_hex(s, UARTCR4, sport);
> +		dump_register_hex(s, UARTCR5, sport);
> +		dump_register_hex(s, UARTMODEM, sport);
> +		dump_register_hex(s, UARTPFIFO, sport);
> +		dump_register_hex(s, UARTCFIFO, sport);
> +		dump_register_hex(s, UARTSFIFO, sport);
> +		dump_register_hex(s, UARTTWFIFO, sport);
> +		dump_register_hex(s, UARTTCFIFO, sport);
> +		dump_register_hex(s, UARTRWFIFO, sport);
> +	}
> +
> +	pm_runtime_mark_last_busy(sport->port.dev);
> +	pm_runtime_put_autosuspend(sport->port.dev);
> +
> +	return 0;
> +}
> +
> +DEFINE_SHOW_ATTRIBUTE(regs);
> +
> +static void lpuart_init_debugfs(struct lpuart_port *sport) {
> +	sport->debugfs_dir = debugfs_create_dir(dev_name(sport-
> >port.dev),
> +						NULL);
> +
> +	debugfs_create_file("regs", 0400, sport->debugfs_dir, sport,
> +&regs_fops); }
> +
> +#else
> +static inline void lpuart_init_debugfs(struct lpuart_port *sport) {}
> +#endif
> +
>  static int lpuart_probe(struct platform_device *pdev)  {
>  	const struct lpuart_soc_data *sdata =
> of_device_get_match_data(&pdev->dev);
> @@ -2969,6 +3035,8 @@ static int lpuart_probe(struct platform_device
> *pdev)
>  	if (ret)
>  		goto failed_irq_request;
> 
> +	lpuart_init_debugfs(sport);
> +
>  	return 0;
> 
>  failed_irq_request:
> @@ -2987,6 +3055,7 @@ static void lpuart_remove(struct platform_device
> *pdev)  {
>  	struct lpuart_port *sport = platform_get_drvdata(pdev);
> 
> +	debugfs_remove_recursive(sport->debugfs_dir);
>  	uart_remove_one_port(&lpuart_reg, &sport->port);
> 
>  	lpuart_disable_clks(sport);
> --
> 2.43.0