CONFIG2_FENAB ('feature enable') changed definition between chip
revisions, from 'Latch SCSI Phase' to 'Latch SCSI Phase, display
chip ID upon reset, and enable 24 bit addresses'.
So only enable it for am53c974 where we know what it's doing.

Signed-off-by: Hannes Reinecke <h...@suse.de>
---
 drivers/scsi/am53c974.c | 30 ++++++++++++++++++++++++++++++
 drivers/scsi/esp_scsi.c |  4 ++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/scsi/am53c974.c b/drivers/scsi/am53c974.c
index 0452ed1..722e781 100644
--- a/drivers/scsi/am53c974.c
+++ b/drivers/scsi/am53c974.c
@@ -252,6 +252,8 @@ static void pci_esp_send_dma_cmd(struct esp *esp, u32 addr, 
u32 esp_count,
 
        pci_esp_write8(esp, (esp_count >> 0) & 0xff, ESP_TCLOW);
        pci_esp_write8(esp, (esp_count >> 8) & 0xff, ESP_TCMED);
+       if (esp->config2 & ESP_CONFIG2_FENAB)
+               pci_esp_write8(esp, (esp_count >> 16) & 0xff, ESP_TCHI);
 
        pci_esp_write32(esp, esp_count, ESP_DMA_STC);
        pci_esp_write32(esp, addr, ESP_DMA_SPA);
@@ -265,6 +267,33 @@ static void pci_esp_send_dma_cmd(struct esp *esp, u32 
addr, u32 esp_count,
        pci_esp_write8(esp, ESP_DMA_CMD_START | val, ESP_DMA_CMD);
 }
 
+static u32 pci_esp_dma_length_limit(struct esp *esp, u32 dma_addr, u32 dma_len)
+{
+       int dma_limit = 16;
+       u32 base, end;
+
+       /*
+        * If CONFIG2_FENAB is set we can
+        * handle up to 24 bit addresses
+        */
+       if (esp->config2 & ESP_CONFIG2_FENAB)
+               dma_limit = 24;
+
+       if (dma_len > (1U << dma_limit))
+               dma_len = (1U << dma_limit);
+
+       /*
+        * Prevent crossing a 24-bit address boundary.
+        */
+       base = dma_addr & ((1U << 24) - 1U);
+       end = base + dma_len;
+       if (end > (1U << 24))
+               end = (1U <<24);
+       dma_len = end - base;
+
+       return dma_len;
+}
+
 static const struct esp_driver_ops pci_esp_ops = {
        .esp_write8     =       pci_esp_write8,
        .esp_read8      =       pci_esp_read8,
@@ -278,6 +307,7 @@ static const struct esp_driver_ops pci_esp_ops = {
        .dma_invalidate =       pci_esp_dma_invalidate,
        .send_dma_cmd   =       pci_esp_send_dma_cmd,
        .dma_error      =       pci_esp_dma_error,
+       .dma_length_limit =     pci_esp_dma_length_limit,
 };
 
 /*
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 01753f5..d0b7b32 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -289,6 +289,8 @@ static void esp_reset_esp(struct esp *esp)
 
        case FAS236:
        case PCSCSI:
+               if (esp->rev == PCSCSI)
+                       esp->config2 |= ESP_CONFIG2_FENAB;
                /* Fast 236, AM53c974 or HME */
                esp_write8(esp->config2, ESP_CFG2);
                if (esp->rev == FASHME) {
@@ -1362,6 +1364,8 @@ static int esp_data_bytes_sent(struct esp *esp, struct 
esp_cmd_entry *ent,
                          (((unsigned int)esp_read8(ESP_TCMED)) << 8));
                if (esp->rev == FASHME)
                        ecount |= ((unsigned int)esp_read8(FAS_RLO)) << 16;
+               if (esp->rev == PCSCSI && (esp->config2 & ESP_CONFIG2_FENAB))
+                       ecount |= ((unsigned int)esp_read8(ESP_TCHI)) << 16;
        }
 
        bytes_sent = esp->data_dma_len;
-- 
1.8.5.2

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