linux-kernel - Re: [PATCH] serial: 8250_pci: Use symbolic constants for EXAR's MPIO registers

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Message-ID: <055cacef-1ab0-0541-030d-d2313763cb2e@siemens.com>
Date:	Tue, 26 Jul 2016 22:44:56 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-serial@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] serial: 8250_pci: Use symbolic constants for EXAR's MPIO
 registers

On 2016-07-26 22:14, Greg Kroah-Hartman wrote:
> On Tue, Jul 26, 2016 at 09:50:37PM +0200, Jan Kiszka wrote:
>> Less magics that only require comments.
>>
>> Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
>> ---
>>  drivers/tty/serial/8250/8250_pci.c | 42 +++++++++++++++++++-------------------
>>  include/uapi/linux/serial_reg.h    | 13 ++++++++++++
>>  2 files changed, 34 insertions(+), 21 deletions(-)
>>
>> diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
>> index c1d4a8f..7f77060 100644
>> --- a/drivers/tty/serial/8250/8250_pci.c
>> +++ b/drivers/tty/serial/8250/8250_pci.c
>> @@ -1796,18 +1796,18 @@ pci_xr17v35x_setup(struct serial_private *priv,
>>  	 * Setup Multipurpose Input/Output pins.
>>  	 */
>>  	if (idx == 0) {
>> -		writeb(0x00, p + 0x8f); /*MPIOINT[7:0]*/
>> -		writeb(0x00, p + 0x90); /*MPIOLVL[7:0]*/
>> -		writeb(0x00, p + 0x91); /*MPIO3T[7:0]*/
>> -		writeb(0x00, p + 0x92); /*MPIOINV[7:0]*/
>> -		writeb(0x00, p + 0x93); /*MPIOSEL[7:0]*/
>> -		writeb(0x00, p + 0x94); /*MPIOOD[7:0]*/
>> -		writeb(0x00, p + 0x95); /*MPIOINT[15:8]*/
>> -		writeb(0x00, p + 0x96); /*MPIOLVL[15:8]*/
>> -		writeb(0x00, p + 0x97); /*MPIO3T[15:8]*/
>> -		writeb(0x00, p + 0x98); /*MPIOINV[15:8]*/
>> -		writeb(0x00, p + 0x99); /*MPIOSEL[15:8]*/
>> -		writeb(0x00, p + 0x9a); /*MPIOOD[15:8]*/
>> +		writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOINT_15_8);
>> +		writeb(0x00, p + UART_EXAR_MPIOLVL_15_8);
>> +		writeb(0x00, p + UART_EXAR_MPIO3T_15_8);
>> +		writeb(0x00, p + UART_EXAR_MPIOINV_15_8);
>> +		writeb(0x00, p + UART_EXAR_MPIOSEL_15_8);
>> +		writeb(0x00, p + UART_EXAR_MPIOOD_15_8);
>>  	}
>>  	writeb(0x00, p + UART_EXAR_8XMODE);
>>  	writeb(UART_FCTR_EXAR_TRGD, p + UART_EXAR_FCTR);
>> @@ -1843,20 +1843,20 @@ pci_fastcom335_setup(struct serial_private *priv,
>>  		switch (priv->dev->device) {
>>  		case PCI_DEVICE_ID_COMMTECH_4222PCI335:
>>  		case PCI_DEVICE_ID_COMMTECH_4224PCI335:
>> -			writeb(0x78, p + 0x90); /* MPIOLVL[7:0] */
>> -			writeb(0x00, p + 0x92); /* MPIOINV[7:0] */
>> -			writeb(0x00, p + 0x93); /* MPIOSEL[7:0] */
>> +			writeb(0x78, p + UART_EXAR_MPIOLVL_7_0);
>> +			writeb(0x00, p + UART_EXAR_MPIOINV_7_0);
>> +			writeb(0x00, p + UART_EXAR_MPIOSEL_7_0);
>>  			break;
>>  		case PCI_DEVICE_ID_COMMTECH_2324PCI335:
>>  		case PCI_DEVICE_ID_COMMTECH_2328PCI335:
>> -			writeb(0x00, p + 0x90); /* MPIOLVL[7:0] */
>> -			writeb(0xc0, p + 0x92); /* MPIOINV[7:0] */
>> -			writeb(0xc0, p + 0x93); /* MPIOSEL[7:0] */
>> +			writeb(0x00, p + UART_EXAR_MPIOLVL_7_0);
>> +			writeb(0xc0, p + UART_EXAR_MPIOINV_7_0);
>> +			writeb(0xc0, p + UART_EXAR_MPIOSEL_7_0);
>>  			break;
>>  		}
>> -		writeb(0x00, p + 0x8f); /* MPIOINT[7:0] */
>> -		writeb(0x00, p + 0x91); /* MPIO3T[7:0] */
>> -		writeb(0x00, p + 0x94); /* MPIOOD[7:0] */
>> +		writeb(0x00, p + UART_EXAR_MPIOINT_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIO3T_7_0);
>> +		writeb(0x00, p + UART_EXAR_MPIOOD_7_0);
>>  	}
>>  	writeb(0x00, p + UART_EXAR_8XMODE);
>>  	writeb(UART_FCTR_EXAR_TRGD, p + UART_EXAR_FCTR);
>> diff --git a/include/uapi/linux/serial_reg.h b/include/uapi/linux/serial_reg.h
>> index 1e5ac4e7..d176448 100644
>> --- a/include/uapi/linux/serial_reg.h
>> +++ b/include/uapi/linux/serial_reg.h
>> @@ -376,5 +376,18 @@
>>  #define UART_EXAR_TXTRG		0x0a	/* Tx FIFO trigger level write-only */
>>  #define UART_EXAR_RXTRG		0x0b	/* Rx FIFO trigger level write-only */
>>  
>> +#define UART_EXAR_MPIOINT_7_0	0x8f	/* MPIOINT[7:0] */
>> +#define UART_EXAR_MPIOLVL_7_0	0x90	/* MPIOLVL[7:0] */
>> +#define UART_EXAR_MPIO3T_7_0	0x91	/* MPIO3T[7:0] */
>> +#define UART_EXAR_MPIOINV_7_0	0x92	/* MPIOINV[7:0] */
>> +#define UART_EXAR_MPIOSEL_7_0	0x93	/* MPIOSEL[7:0] */
>> +#define UART_EXAR_MPIOOD_7_0	0x94	/* MPIOOD[7:0] */
>> +#define UART_EXAR_MPIOINT_15_8	0x95	/* MPIOINT[15:8] */
>> +#define UART_EXAR_MPIOLVL_15_8	0x96	/* MPIOLVL[15:8] */
>> +#define UART_EXAR_MPIO3T_15_8	0x97	/* MPIO3T[15:8] */
>> +#define UART_EXAR_MPIOINV_15_8	0x98	/* MPIOINV[15:8] */
>> +#define UART_EXAR_MPIOSEL_15_8	0x99	/* MPIOSEL[15:8] */
>> +#define UART_EXAR_MPIOOD_15_8	0x9a	/* MPIOOD[15:8] */
>> +
> 
> Why are you putting these in a user api file?  I know it matches the
> existing ones, but is this something that userspace really cares about?

Very valid question, and I was wondering the same. Maybe 95% of this
header is just lazy leftover from 607ca46e97.

I'm fine with starting off some include/linux/serial_reg.h, provided
someone gives me a hint what should be moved - I'm not very familiar
with the serial kernel ABI. Or I just start it off with those defines
above. You choose.

Jan

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