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-rw-r--r--drivers/scsi/atari_dma_emul.c466
1 files changed, 466 insertions, 0 deletions
diff --git a/drivers/scsi/atari_dma_emul.c b/drivers/scsi/atari_dma_emul.c
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+/*
+ * atari_dma_emul.c -- TT SCSI DMA emulator for the Hades.
+ *
+ * Copyright 1997 Wout Klaren <W.Klaren@inter.nl.net>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file COPYING in the main directory of this archive
+ * for more details.
+ *
+ * This code was written using the Hades TOS source code as a
+ * reference. This source code can be found on the home page
+ * of Medusa Computer Systems.
+ *
+ * Version 0.1, 1997-09-24.
+ *
+ * This code should be considered experimental. It has only been
+ * tested on a Hades with a 68060. It might not work on a Hades
+ * with a 68040. Make backups of your hard drives before using
+ * this code.
+ */
+
+#include <asm/uaccess.h>
+
+#define hades_dma_ctrl (*(unsigned char *) 0xffff8717)
+#define hades_psdm_reg (*(unsigned char *) 0xffff8741)
+
+#define TRANSFER_SIZE 16
+
+struct m68040_frame {
+ unsigned long effaddr; /* effective address */
+ unsigned short ssw; /* special status word */
+ unsigned short wb3s; /* write back 3 status */
+ unsigned short wb2s; /* write back 2 status */
+ unsigned short wb1s; /* write back 1 status */
+ unsigned long faddr; /* fault address */
+ unsigned long wb3a; /* write back 3 address */
+ unsigned long wb3d; /* write back 3 data */
+ unsigned long wb2a; /* write back 2 address */
+ unsigned long wb2d; /* write back 2 data */
+ unsigned long wb1a; /* write back 1 address */
+ unsigned long wb1dpd0; /* write back 1 data/push data 0*/
+ unsigned long pd1; /* push data 1*/
+ unsigned long pd2; /* push data 2*/
+ unsigned long pd3; /* push data 3*/
+};
+
+static void writeback (unsigned short wbs, unsigned long wba,
+ unsigned long wbd, void *old_buserr)
+{
+ mm_segment_t fs = get_fs();
+ static void *save_buserr;
+
+ __asm__ __volatile__ ("movec.l %%vbr,%%a0\n\t"
+ "move.l %0,8(%%a0)\n\t"
+ :
+ : "r" (&&bus_error)
+ : "a0" );
+
+ save_buserr = old_buserr;
+
+ set_fs (MAKE_MM_SEG(wbs & WBTM_040));
+
+ switch (wbs & WBSIZ_040) {
+ case BA_SIZE_BYTE:
+ put_user (wbd & 0xff, (char *)wba);
+ break;
+ case BA_SIZE_WORD:
+ put_user (wbd & 0xffff, (short *)wba);
+ break;
+ case BA_SIZE_LONG:
+ put_user (wbd, (int *)wba);
+ break;
+ }
+
+ set_fs (fs);
+ return;
+
+bus_error:
+ __asm__ __volatile__ ("cmp.l %0,2(%%sp)\n\t"
+ "bcs.s .jump_old\n\t"
+ "cmp.l %1,2(%%sp)\n\t"
+ "bls.s .restore_old\n"
+ ".jump_old:\n\t"
+ "move.l %2,-(%%sp)\n\t"
+ "rts\n"
+ ".restore_old:\n\t"
+ "move.l %%a0,-(%%sp)\n\t"
+ "movec.l %%vbr,%%a0\n\t"
+ "move.l %2,8(%%a0)\n\t"
+ "move.l (%%sp)+,%%a0\n\t"
+ "rte\n\t"
+ :
+ : "i" (writeback), "i" (&&bus_error),
+ "m" (save_buserr) );
+}
+
+/*
+ * static inline void set_restdata_reg(unsigned char *cur_addr)
+ *
+ * Set the rest data register if necessary.
+ */
+
+static inline void set_restdata_reg(unsigned char *cur_addr)
+{
+ if (((long) cur_addr & ~3) != 0)
+ tt_scsi_dma.dma_restdata =
+ *((unsigned long *) ((long) cur_addr & ~3));
+}
+
+/*
+ * void hades_dma_emulator(int irq, void *dummy, struct pt_regs *fp)
+ *
+ * This code emulates TT SCSI DMA on the Hades.
+ *
+ * Note the following:
+ *
+ * 1. When there is no byte available to read from the SCSI bus, or
+ * when a byte cannot yet bet written to the SCSI bus, a bus
+ * error occurs when reading or writing the pseudo DMA data
+ * register (hades_psdm_reg). We have to catch this bus error
+ * and try again to read or write the byte. If after several tries
+ * we still get a bus error, the interrupt handler is left. When
+ * the byte can be read or written, the interrupt handler is
+ * called again.
+ *
+ * 2. The SCSI interrupt must be disabled in this interrupt handler.
+ *
+ * 3. If we set the EOP signal, the SCSI controller still expects one
+ * byte to be read or written. Therefore the last byte is transferred
+ * separately, after setting the EOP signal.
+ *
+ * 4. When this function is left, the address pointer (start_addr) is
+ * converted to a physical address. Because it points one byte
+ * further than the last transfered byte, it can point outside the
+ * current page. If virt_to_phys() is called with this address we
+ * might get an access error. Therefore virt_to_phys() is called with
+ * start_addr - 1 if the count has reached zero. The result is
+ * increased with one.
+ */
+
+static void hades_dma_emulator(int irq, void *dummy, struct pt_regs *fp)
+{
+ unsigned long dma_base;
+ register unsigned long dma_cnt asm ("d3");
+ static long save_buserr;
+ register unsigned long save_sp asm ("d4");
+ register int tries asm ("d5");
+ register unsigned char *start_addr asm ("a3"), *end_addr asm ("a4");
+ register unsigned char *eff_addr;
+ register unsigned char *psdm_reg;
+ unsigned long rem;
+
+ atari_disable_irq(IRQ_TT_MFP_SCSI);
+
+ /*
+ * Read the dma address and count registers.
+ */
+
+ dma_base = SCSI_DMA_READ_P(dma_addr);
+ dma_cnt = SCSI_DMA_READ_P(dma_cnt);
+
+ /*
+ * Check if DMA is still enabled.
+ */
+
+ if ((tt_scsi_dma.dma_ctrl & 2) == 0)
+ {
+ atari_enable_irq(IRQ_TT_MFP_SCSI);
+ return;
+ }
+
+ if (dma_cnt == 0)
+ {
+ printk(KERN_NOTICE "DMA emulation: count is zero.\n");
+ tt_scsi_dma.dma_ctrl &= 0xfd; /* DMA ready. */
+ atari_enable_irq(IRQ_TT_MFP_SCSI);
+ return;
+ }
+
+ /*
+ * Install new bus error routine.
+ */
+
+ __asm__ __volatile__ ("movec.l %%vbr,%%a0\n\t"
+ "move.l 8(%%a0),%0\n\t"
+ "move.l %1,8(%%a0)\n\t"
+ : "=&r" (save_buserr)
+ : "r" (&&scsi_bus_error)
+ : "a0" );
+
+ hades_dma_ctrl &= 0xfc; /* Bus error and EOP off. */
+
+ /*
+ * Save the stack pointer.
+ */
+
+ __asm__ __volatile__ ("move.l %%sp,%0\n\t"
+ : "=&r" (save_sp) );
+
+ tries = 100; /* Maximum number of bus errors. */
+ start_addr = phys_to_virt(dma_base);
+ end_addr = start_addr + dma_cnt;
+
+scsi_loop:
+ dma_cnt--;
+ rem = dma_cnt & (TRANSFER_SIZE - 1);
+ dma_cnt &= ~(TRANSFER_SIZE - 1);
+ psdm_reg = &hades_psdm_reg;
+
+ if (tt_scsi_dma.dma_ctrl & 1) /* Read or write? */
+ {
+ /*
+ * SCSI write. Abort when count is zero.
+ */
+
+ switch (rem)
+ {
+ case 0:
+ while (dma_cnt > 0)
+ {
+ dma_cnt -= TRANSFER_SIZE;
+
+ *psdm_reg = *start_addr++;
+ case 15:
+ *psdm_reg = *start_addr++;
+ case 14:
+ *psdm_reg = *start_addr++;
+ case 13:
+ *psdm_reg = *start_addr++;
+ case 12:
+ *psdm_reg = *start_addr++;
+ case 11:
+ *psdm_reg = *start_addr++;
+ case 10:
+ *psdm_reg = *start_addr++;
+ case 9:
+ *psdm_reg = *start_addr++;
+ case 8:
+ *psdm_reg = *start_addr++;
+ case 7:
+ *psdm_reg = *start_addr++;
+ case 6:
+ *psdm_reg = *start_addr++;
+ case 5:
+ *psdm_reg = *start_addr++;
+ case 4:
+ *psdm_reg = *start_addr++;
+ case 3:
+ *psdm_reg = *start_addr++;
+ case 2:
+ *psdm_reg = *start_addr++;
+ case 1:
+ *psdm_reg = *start_addr++;
+ }
+ }
+
+ hades_dma_ctrl |= 1; /* Set EOP. */
+ udelay(10);
+ *psdm_reg = *start_addr++; /* Dummy byte. */
+ tt_scsi_dma.dma_ctrl &= 0xfd; /* DMA ready. */
+ }
+ else
+ {
+ /*
+ * SCSI read. Abort when count is zero.
+ */
+
+ switch (rem)
+ {
+ case 0:
+ while (dma_cnt > 0)
+ {
+ dma_cnt -= TRANSFER_SIZE;
+
+ *start_addr++ = *psdm_reg;
+ case 15:
+ *start_addr++ = *psdm_reg;
+ case 14:
+ *start_addr++ = *psdm_reg;
+ case 13:
+ *start_addr++ = *psdm_reg;
+ case 12:
+ *start_addr++ = *psdm_reg;
+ case 11:
+ *start_addr++ = *psdm_reg;
+ case 10:
+ *start_addr++ = *psdm_reg;
+ case 9:
+ *start_addr++ = *psdm_reg;
+ case 8:
+ *start_addr++ = *psdm_reg;
+ case 7:
+ *start_addr++ = *psdm_reg;
+ case 6:
+ *start_addr++ = *psdm_reg;
+ case 5:
+ *start_addr++ = *psdm_reg;
+ case 4:
+ *start_addr++ = *psdm_reg;
+ case 3:
+ *start_addr++ = *psdm_reg;
+ case 2:
+ *start_addr++ = *psdm_reg;
+ case 1:
+ *start_addr++ = *psdm_reg;
+ }
+ }
+
+ hades_dma_ctrl |= 1; /* Set EOP. */
+ udelay(10);
+ *start_addr++ = *psdm_reg;
+ tt_scsi_dma.dma_ctrl &= 0xfd; /* DMA ready. */
+
+ set_restdata_reg(start_addr);
+ }
+
+ if (start_addr != end_addr)
+ printk(KERN_CRIT "DMA emulation: FATAL: Count is not zero at end of transfer.\n");
+
+ dma_cnt = end_addr - start_addr;
+
+scsi_end:
+ dma_base = (dma_cnt == 0) ? virt_to_phys(start_addr - 1) + 1 :
+ virt_to_phys(start_addr);
+
+ SCSI_DMA_WRITE_P(dma_addr, dma_base);
+ SCSI_DMA_WRITE_P(dma_cnt, dma_cnt);
+
+ /*
+ * Restore old bus error routine.
+ */
+
+ __asm__ __volatile__ ("movec.l %%vbr,%%a0\n\t"
+ "move.l %0,8(%%a0)\n\t"
+ :
+ : "r" (save_buserr)
+ : "a0" );
+
+ atari_enable_irq(IRQ_TT_MFP_SCSI);
+
+ return;
+
+scsi_bus_error:
+ /*
+ * First check if the bus error is caused by our code.
+ * If not, call the original handler.
+ */
+
+ __asm__ __volatile__ ("cmp.l %0,2(%%sp)\n\t"
+ "bcs.s .old_vector\n\t"
+ "cmp.l %1,2(%%sp)\n\t"
+ "bls.s .scsi_buserr\n"
+ ".old_vector:\n\t"
+ "move.l %2,-(%%sp)\n\t"
+ "rts\n"
+ ".scsi_buserr:\n\t"
+ :
+ : "i" (&&scsi_loop), "i" (&&scsi_end),
+ "m" (save_buserr) );
+
+ if (CPU_IS_060)
+ {
+ /*
+ * Get effective address and restore the stack.
+ */
+
+ __asm__ __volatile__ ("move.l 8(%%sp),%0\n\t"
+ "move.l %1,%%sp\n\t"
+ : "=a&" (eff_addr)
+ : "r" (save_sp) );
+ }
+ else
+ {
+ register struct m68040_frame *frame;
+
+ __asm__ __volatile__ ("lea 8(%%sp),%0\n\t"
+ : "=a&" (frame) );
+
+ if (tt_scsi_dma.dma_ctrl & 1)
+ {
+ /*
+ * Bus error while writing.
+ */
+
+ if (frame->wb3s & WBV_040)
+ {
+ if (frame->wb3a == (long) &hades_psdm_reg)
+ start_addr--;
+ else
+ writeback(frame->wb3s, frame->wb3a,
+ frame->wb3d, &&scsi_bus_error);
+ }
+
+ if (frame->wb2s & WBV_040)
+ {
+ if (frame->wb2a == (long) &hades_psdm_reg)
+ start_addr--;
+ else
+ writeback(frame->wb2s, frame->wb2a,
+ frame->wb2d, &&scsi_bus_error);
+ }
+
+ if (frame->wb1s & WBV_040)
+ {
+ if (frame->wb1a == (long) &hades_psdm_reg)
+ start_addr--;
+ }
+ }
+ else
+ {
+ /*
+ * Bus error while reading.
+ */
+
+ if (frame->wb3s & WBV_040)
+ writeback(frame->wb3s, frame->wb3a,
+ frame->wb3d, &&scsi_bus_error);
+ }
+
+ eff_addr = (unsigned char *) frame->faddr;
+
+ __asm__ __volatile__ ("move.l %0,%%sp\n\t"
+ :
+ : "r" (save_sp) );
+ }
+
+ dma_cnt = end_addr - start_addr;
+
+ if (eff_addr == &hades_psdm_reg)
+ {
+ /*
+ * Bus error occured while reading the pseudo
+ * DMA register. Time out.
+ */
+
+ tries--;
+
+ if (tries <= 0)
+ {
+ if ((tt_scsi_dma.dma_ctrl & 1) == 0) /* Read or write? */
+ set_restdata_reg(start_addr);
+
+ if (dma_cnt <= 1)
+ printk(KERN_CRIT "DMA emulation: Fatal "
+ "error while %s the last byte.\n",
+ (tt_scsi_dma.dma_ctrl & 1)
+ ? "writing" : "reading");
+
+ goto scsi_end;
+ }
+ else
+ goto scsi_loop;
+ }
+ else
+ {
+ /*
+ * Bus error during pseudo DMA transfer.
+ * Terminate the DMA transfer.
+ */
+
+ hades_dma_ctrl |= 3; /* Set EOP and bus error. */
+ if ((tt_scsi_dma.dma_ctrl & 1) == 0) /* Read or write? */
+ set_restdata_reg(start_addr);
+ goto scsi_end;
+ }
+}
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