[SeaBIOS] [PATCH] Fixes to the floppy driver, so it works on real (not emulated) hardware
Kevin O'Connor
kevin at koconnor.net
Wed Jan 31 04:23:16 CET 2018
On Tue, Jan 30, 2018 at 05:41:47AM +0200, Nikolay Nikolov wrote:
> Several fixes to the floppy driver, so it works on a real floppy controller
> with a real floppy. Tested with Coreboot on a motherboard with an ITE IT8712
> Super I/O chip (and its built-in floppy controller) and a 1.44MB floppy.
>
> Only one floppy is supported for now and only 1.44MB, but more formats will be
> added in the future.
Thanks. See my comments below.
> --- a/src/hw/floppy.c
> +++ b/src/hw/floppy.c
> @@ -34,6 +34,11 @@
> #define FLOPPY_GAPLEN 0x1B
> #define FLOPPY_FORMAT_GAPLEN 0x6c
> #define FLOPPY_PIO_TIMEOUT 1000
> +#define FLOPPY_IRQ_TIMEOUT 5000
> +#define FLOPPY_STARTUP_TIME 8
> +#define FLOPPY_MOTOR_HOLD 255 // Magic value, means motor must not be turned off
> +#define FLOPPY_SPECIFY1 0xAF // step rate 12ms, head unload 240ms
> +#define FLOPPY_SPECIFY2 0x02 // head load time 4ms, DMA used
It would be good to also update diskette_param_table2 with these new
variables (as is done for the other variables).
>
> // New diskette parameter table adding 3 parameters from IBM
> // Since no provisions are made for multiple drive types, most
> @@ -191,7 +196,8 @@ static void
> floppy_disable_controller(void)
> {
> dprintf(2, "Floppy_disable_controller\n");
> - floppy_dor_write(0x00);
> + // Clear the reset bit (enter reset state) and clear 'enable IRQ and DMA'
> + floppy_dor_write(GET_LOW(FloppyDOR) & ~0x0c);
Why do this? What state needs to preserved in the DOR register on a
disable?
> @@ -199,8 +205,9 @@ floppy_wait_irq(void)
> {
> u8 frs = GET_BDA(floppy_recalibration_status);
> SET_BDA(floppy_recalibration_status, frs & ~FRS_IRQ);
> + u32 end = timer_calc(FLOPPY_IRQ_TIMEOUT);
> for (;;) {
> - if (!GET_BDA(floppy_motor_counter)) {
> + if (timer_check(end)) {
The floppy_motor_counter is an external variable that some legacy
programs may inspect. I'm not sure we can not update it here. What's
the reason for changing the timeout to use timer_calc()?
> warn_timeout();
> floppy_disable_controller();
> return DISK_RET_ETIMEOUT;
> @@ -226,6 +233,7 @@ floppy_wait_irq(void)
> #define FC_READ (0xe6 | (8<<8) | (7<<12) | FCF_WAITIRQ)
> #define FC_WRITE (0xc5 | (8<<8) | (7<<12) | FCF_WAITIRQ)
> #define FC_FORMAT (0x4d | (5<<8) | (7<<12) | FCF_WAITIRQ)
> +#define FC_SPECIFY (0x03 | (2<<8) | (0<<12))
>
> // Send the specified command and it's parameters to the floppy controller.
> static int
> @@ -302,9 +310,12 @@ static int
> floppy_enable_controller(void)
> {
> dprintf(2, "Floppy_enable_controller\n");
> - SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);
> - floppy_dor_write(0x00);
> - floppy_dor_write(0x0c);
> + // Clear the reset bit (enter reset state), but set 'enable IRQ and DMA'
> + floppy_dor_write((GET_LOW(FloppyDOR) & ~0x04) | 0x08);
> + // Real hardware needs a 4 microsecond delay
> + udelay(4);
Can this be a usleep()?
> + // Set the reset bit (normal operation) and keep 'enable IRQ and DMA' on
> + floppy_dor_write(GET_LOW(FloppyDOR) | 0x0c);
> int ret = floppy_wait_irq();
> if (ret)
> return ret;
> @@ -313,6 +324,30 @@ floppy_enable_controller(void)
> return floppy_pio(FC_CHECKIRQ, param);
> }
>
> +static void
> +floppy_turn_on_motor(u8 floppyid)
> +{
> + // prevent the motor from being turned off
> + SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_HOLD);
I don't see a reference to 255 being a special value in the bios docs
for floppy_motor_counter. As above, this is an external variable and
I'm not sure we can change it to custom values. Did you find a
reference to it in a specification?
> +
> + u8 motor_mask = 0x10 << floppyid;
> + if (GET_LOW(FloppyDOR) & motor_mask) {
> + // If the motor has been started, there's no need to wait for it again
> + floppy_dor_write(motor_mask | 0x0c | floppyid);
> + } else {
> + floppy_dor_write(motor_mask | 0x0c | floppyid);
> +
> + msleep(FLOPPY_STARTUP_TIME * 125);
> + }
> +}
> +
> +static void
> +floppy_turn_off_motor_delayed(void)
> +{
> + // reset the disk motor timeout value of INT 08
> + SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);
> +}
> +
> // Activate a drive and send a command to it.
> static int
> floppy_drive_pio(u8 floppyid, int command, u8 *param)
> @@ -324,11 +359,8 @@ floppy_drive_pio(u8 floppyid, int command, u8 *param)
> return ret;
> }
>
> - // reset the disk motor timeout value of INT 08
> - SET_BDA(floppy_motor_counter, FLOPPY_MOTOR_TICKS);
> -
> - // Turn on motor of selected drive, DMA & int enabled, normal operation
> - floppy_dor_write((floppyid ? 0x20 : 0x10) | 0x0c | floppyid);
> + // Turn on motor of selected drive and wait for it to get up to speed
> + floppy_turn_on_motor(floppyid);
>
> // Send command.
> int ret = floppy_pio(command, param);
> @@ -363,6 +395,15 @@ floppy_drive_recal(u8 floppyid)
> return DISK_RET_SUCCESS;
> }
>
> +static int
> +floppy_drive_specify(void)
> +{
> + u8 param[2];
> + param[0] = FLOPPY_SPECIFY1;
> + param[1] = FLOPPY_SPECIFY2;
> + return floppy_pio(FC_SPECIFY, param);
> +}
> +
> static int
> floppy_drive_readid(u8 floppyid, u8 data_rate, u8 head)
> {
> @@ -433,13 +474,23 @@ floppy_prep(struct drive_s *drive_gf, u8 cylinder)
> !(GET_BDA(floppy_media_state[floppyid]) & FMS_MEDIA_DRIVE_ESTABLISHED)) {
> // Recalibrate drive.
> int ret = floppy_drive_recal(floppyid);
> - if (ret)
> + if (ret) {
> + floppy_turn_off_motor_delayed();
> return ret;
> + }
>
> // Sense media.
> ret = floppy_media_sense(drive_gf);
> - if (ret)
> + if (ret) {
> + floppy_turn_off_motor_delayed();
> + return ret;
> + }
> +
> + ret = floppy_drive_specify();
> + if (ret) {
> + floppy_turn_off_motor_delayed();
> return ret;
> + }
> }
>
> // Seek to cylinder if needed.
> @@ -449,8 +500,10 @@ floppy_prep(struct drive_s *drive_gf, u8 cylinder)
> param[0] = floppyid;
> param[1] = cylinder;
> int ret = floppy_drive_pio(floppyid, FC_SEEK, param);
> - if (ret)
> + if (ret) {
> + floppy_turn_off_motor_delayed();
> return ret;
> + }
> SET_BDA(floppy_track[floppyid], cylinder);
> }
>
> @@ -489,9 +542,11 @@ floppy_dma_cmd(struct disk_op_s *op, int count, int command, u8 *param)
> dprintf(1, "floppy error: %02x %02x %02x %02x %02x %02x %02x\n"
> , param[0], param[1], param[2], param[3]
> , param[4], param[5], param[6]);
> + floppy_turn_off_motor_delayed();
> return DISK_RET_ECONTROLLER;
> }
>
> + floppy_turn_off_motor_delayed();
> return DISK_RET_SUCCESS;
> }
>
> @@ -663,7 +718,7 @@ floppy_tick(void)
>
> // time to turn off drive(s)?
> u8 fcount = GET_BDA(floppy_motor_counter);
> - if (fcount) {
> + if (fcount && (fcount != FLOPPY_MOTOR_HOLD)) {
> fcount--;
> SET_BDA(floppy_motor_counter, fcount);
> if (fcount == 0)
-Kevin
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