Re: [Qemu-devel] [PATCH] SM501 emulation for R2D-SH4

["Blue Swirl" <blauwirbel@gmail.com>]

On 11/2/08, Shin-ichiro KAWASAKI <kawasaki@juno.dti.ne.jp> wrote:
> Hi, all!
>
>  This patch adds minimum emulation of SM501 multifunction device,
>  whose main feature is 2D graphics.  It is one of the peripheral
>  of R2D, the SH4 evaluation board.  We can see TUX printed on the
>  QEMU console.

>  +#define UART_RX_OFFSET  0x00
>  +#define UART_TX_OFFSET  0x00
>  +#define UART_IER_OFFSET 0x04
>  +#define UART_IIR_OFFSET 0x08
>  +#define UART_FCR_OFFSET 0x08
>  +#define UART_LCR_OFFSET 0x0C
>  +#define UART_MCR_OFFSET 0x10
>  +#define UART_LSR_OFFSET 0x14
>  +#define UART_MSR_OFFSET 0x18
>  +#define UART_SCR_OFFSET 0x1C

Looks like standard 16550-like UART. Maybe you could use the version
in serial.c and map that to this location?

>  +/* taken from "linux/drivers/mfd/sm501.c" */
>  +static uint32_t sm501_mem_local_size[] = {

"const"?

>  +    if (SM501_DC + SM501_DC_PANEL_PALETTE <= offset
>  +       && offset < SM501_DC + SM501_DC_VIDEO_PALETTE) {
>  +       offset -= SM501_DC + SM501_DC_PANEL_PALETTE;
>  +       /* TODO : consider BYTE/WORD access */
>  +       /* TODO : consider endian */
>  +       ret = *(uint32_t*)&s->dc_panel_palette[offset];
>  +    } else if (SM501_DC + SM501_DC_VIDEO_PALETTE <= offset
>  +              && offset < SM501_DC + SM501_DC_CRT_PALETTE) {
>  +       offset -= SM501_DC + SM501_DC_VIDEO_PALETTE;
>  +       /* TODO : consider BYTE/WORD access */
>  +       /* TODO : consider endian */
>  +       ret = *(uint32_t*)&s->dc_video_palette[offset];
>  +    } else if (SM501_DC + SM501_DC_CRT_PALETTE <= offset
>  +              && offset < SM501_DC + SM501_DC_CRT_PALETTE + 0x400) {
>  +       offset -= SM501_DC + SM501_DC_CRT_PALETTE;
>  +       /* TODO : consider BYTE/WORD access */
>  +       /* TODO : consider endian */
>  +       ret = *(uint32_t*)&s->dc_crt_palette[offset];
>  +    } else {

The above should be cleaner and faster if you registered different
access routines for each area.

>  +static uint32_t sm501_lm_read(void *opaque, target_phys_addr_t addr)
>  +{
>  +    SM501State * s = (SM501State *)opaque;
>  +    uint32_t offset = addr - s->base;
>  +    return *(uint32_t*)&s->local_mem[offset];
>  +}

It would be much faster to register normal RAM for this area and check
for updated pages asynchronously using VGA_DIRTY_FLAG (see vga.c or
tcx.c).

>  +    /* allocate local memory */
>  +    s->local_mem = qemu_mallocz(get_local_mem_size(s));

The display buffer should be allocated using machine definition .ram_require.