Blackfin: fix early L1 relocation crash

Our early L1 relocate code may implicitly call code which lives in L1
memory.  This is due to the dma_memcpy() rewrite that made the DMA code
lockless and safe to be used by multiple processes.  If we start the
early DMA memcpy to relocate things into L1 instruction but then our
DMA memcpy code calls a function that lives in L1, things fall apart.
As such, create a small dedicated DMA memcpy routine that we can assume
sanity at boot time.

Reported-by: Filip Van Rillaer <filip.vanrillaer@oneaccess-net.com>
Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>

1 files changed, 81 insertions, 0 deletions

diff --git a/arch/blackfin/kernel/bfin_dma_5xx.c b/arch/blackfin/kernel/bfin_dma_5xx.c
index 8531693fb48d..704419e4da20 100644
--- a/arch/blackfin/kernel/bfin_dma_5xx.c
+++ b/arch/blackfin/kernel/bfin_dma_5xx.c
@@ -232,6 +232,87 @@ void blackfin_dma_resume(void)
 void __init blackfin_dma_early_init(void)
 {
         bfin_write_MDMA_S0_CONFIG(0);
+        bfin_write_MDMA_S1_CONFIG(0);
+}
+
+void __init early_dma_memcpy(void *pdst, const void *psrc, size_t size)
+{
+        unsigned long dst = (unsigned long)pdst;
+        unsigned long src = (unsigned long)psrc;
+        struct dma_register *dst_ch, *src_ch;
+
+        /* We assume that everything is 4 byte aligned, so include
+         * a basic sanity check
+         */
+        BUG_ON(dst % 4);
+        BUG_ON(src % 4);
+        BUG_ON(size % 4);
+
+        /* Force a sync in case a previous config reset on this channel
+         * occurred.  This is needed so subsequent writes to DMA registers
+         * are not spuriously lost/corrupted.
+         */
+        __builtin_bfin_ssync();
+
+        src_ch = 0;
+        /* Find an avalible memDMA channel */
+        while (1) {
+                if (!src_ch || src_ch == (struct dma_register *)MDMA_S1_NEXT_DESC_PTR) {
+                        dst_ch = (struct dma_register *)MDMA_D0_NEXT_DESC_PTR;
+                        src_ch = (struct dma_register *)MDMA_S0_NEXT_DESC_PTR;
+                } else {
+                        dst_ch = (struct dma_register *)MDMA_D1_NEXT_DESC_PTR;
+                        src_ch = (struct dma_register *)MDMA_S1_NEXT_DESC_PTR;
+                }
+
+                if (!bfin_read16(&src_ch->cfg)) {
+                        break;
+                } else {
+                        if (bfin_read16(&src_ch->irq_status) & DMA_DONE)
+                                bfin_write16(&src_ch->cfg, 0);
+                }
+
+        }
+
+        /* Destination */
+        bfin_write32(&dst_ch->start_addr, dst);
+        bfin_write16(&dst_ch->x_count, size >> 2);
+        bfin_write16(&dst_ch->x_modify, 1 << 2);
+        bfin_write16(&dst_ch->irq_status, DMA_DONE | DMA_ERR);
+
+        /* Source */
+        bfin_write32(&src_ch->start_addr, src);
+        bfin_write16(&src_ch->x_count, size >> 2);
+        bfin_write16(&src_ch->x_modify, 1 << 2);
+        bfin_write16(&src_ch->irq_status, DMA_DONE | DMA_ERR);
+
+        /* Enable */
+        bfin_write16(&src_ch->cfg, DMAEN | WDSIZE_32);
+        bfin_write16(&dst_ch->cfg, WNR | DI_EN | DMAEN | WDSIZE_32);
+
+        /* Since we are atomic now, don't use the workaround ssync */
+        __builtin_bfin_ssync();
+}
+
+void __init early_dma_memcpy_done(void)
+{
+        while ((bfin_read_MDMA_S0_CONFIG() && !(bfin_read_MDMA_D0_IRQ_STATUS() & DMA_DONE)) ||
+               (bfin_read_MDMA_S1_CONFIG() && !(bfin_read_MDMA_D1_IRQ_STATUS() & DMA_DONE)))
+                continue;
+
+        bfin_write_MDMA_D0_IRQ_STATUS(DMA_DONE | DMA_ERR);
+        bfin_write_MDMA_D1_IRQ_STATUS(DMA_DONE | DMA_ERR);
+        /*
+         * Now that DMA is done, we would normally flush cache, but
+         * i/d cache isn't running this early, so we don't bother,
+         * and just clear out the DMA channel for next time
+         */
+        bfin_write_MDMA_S0_CONFIG(0);
+        bfin_write_MDMA_S1_CONFIG(0);
+        bfin_write_MDMA_D0_CONFIG(0);
+        bfin_write_MDMA_D1_CONFIG(0);
+
+        __builtin_bfin_ssync();
 }
 
 /**