Date: Wed, 16 Jan 2013 17:43:09 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: "Wojciech A. Koszek" <wkoszek@FreeBSD.org> Cc: svn-src-head@FreeBSD.org, Ganbold Tsagaankhuu <ganbold@FreeBSD.org>, svn-src-all@FreeBSD.org, src-committers@FreeBSD.org Subject: Re: svn commit: r245450 - in head/sys: arm/allwinner arm/conf boot/fdt/dts Message-ID: <20130116170419.G1725@besplex.bde.org> In-Reply-To: <20130115162116.GI20538@FreeBSD.org> References: <201301150826.r0F8QGJr044600@svn.freebsd.org> <20130115162116.GI20538@FreeBSD.org>
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On Tue, 15 Jan 2013, Wojciech A. Koszek wrote:
> On Tue, Jan 15, 2013 at 08:26:16AM +0000, Ganbold Tsagaankhuu wrote:
>> ...
>> Added: head/sys/arm/allwinner/console.c
>> ==============================================================================
>> --- /dev/null 00:00:00 1970 (empty, because file is newly added)
>> +++ head/sys/arm/allwinner/console.c Tue Jan 15 08:26:16 2013 (r245450)
>> @@ -0,0 +1,146 @@
> [..]
>> +#ifndef A10_UART_BASE
>> +#define A10_UART_BASE 0xe1c28000 /* UART0 */
>> +#endif
>> +
>> +int reg_shift = 2;
>
> Could you make it static and move it below defines?
>
>> +#define UART_DLL 0 /* Out: Divisor Latch Low */
>> +#define UART_DLM 1 /* Out: Divisor Latch High */
>> +#define UART_FCR 2 /* Out: FIFO Control Register */
>> +#define UART_LCR 3 /* Out: Line Control Register */
>> +#define UART_MCR 4 /* Out: Modem Control Register */
>> +#define UART_LSR 5 /* In: Line Status Register */
>> +#define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
>> +#define UART_LSR_DR 0x01 /* Receiver data ready */
>> +#define UART_MSR 6 /* In: Modem Status Register */
>> +#define UART_SCR 7 /* I/O: Scratch Register */
These are ordinary 16450 values which are defined in <ic/ns16550.h>.
This is misformatted with a space instead of a tab after #define.
Since it's a 16450, uart(4) can probably handle the entire console driver,
with fewer bugs (some locking is required in a general console driver).
Of course, it's easier to write a primitive console driver by hacking on
the raw registers than to interface with uart.
>> +
>> +
>> +/*
>> + * uart related funcs
>> + */
Style bugs (extra and missing blank lines, and comment punctuation).
>> +static u_int32_t
>> +uart_getreg(u_int32_t *bas)
>> +{
>> + return *((volatile u_int32_t *)(bas)) & 0xff;
>> +}
It's better to put the reg_shift complications at the lowest level.
reg_shift could probably be const or #defined so that all the calculations
with it can be done at runtime.
>> +
>> +static void
>> +uart_setreg(u_int32_t *bas, u_int32_t val)
>> +{
>> + *((volatile u_int32_t *)(bas)) = (u_int32_t)val;
>> +}
Bogus cast. val already has type u_int32_t. u_int32_t should be spelled
uint32_t in new code.
>> +
>> +static int
>> +ub_getc(void)
>> +{
>> + while ((uart_getreg((u_int32_t *)(A10_UART_BASE +
>> + (UART_LSR << reg_shift))) & UART_LSR_DR) == 0);
>> + __asm __volatile("nop");
>> +
>> + return (uart_getreg((u_int32_t *)A10_UART_BASE) & 0xff);
>> +}
>> +
>> +static void
>> +ub_putc(unsigned char c)
>> +{
>> + if (c == '\n')
>> + ub_putc('\r');
The normal console driver does this in upper layers. Is this driver
only for a very specialized console driver for use at boot time?
I'm not sure if uart(4) works then.
>> +
>> + while ((uart_getreg((u_int32_t *)(A10_UART_BASE +
>> + (UART_LSR << reg_shift))) & UART_LSR_THRE) == 0)
>> + __asm __volatile("nop");
>> +
>> + uart_setreg((u_int32_t *)A10_UART_BASE, c);
>> +}
>
> Why aren't bus_* methods used here for accessing memory?
They don't support reg_shift, but should work otherwise. You do the
shifting somewhere and then use bus-space at the level of uart_getreg()
above.
Bruce
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