2 files changed, 42 insertions, 0 deletions

diff --git a/drivers/scsi/am53c974.c b/drivers/scsi/am53c974.c
index 6e88e38bd2a4..25f06196643e 100644
--- a/drivers/scsi/am53c974.c
+++ b/drivers/scsi/am53c974.c
@@ -18,6 +18,7 @@
 #define DRV_MODULE_VERSION "1.00"
 
 static bool am53c974_debug;
+static bool am53c974_fenab = true;
 
 #define esp_dma_log(f, a...)                                            \
         do {                                                            \
@@ -256,6 +257,8 @@ 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);
@@ -268,6 +271,33 @@ 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,
@@ -281,6 +311,7 @@ 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,
 };
 
 /*
@@ -418,6 +449,12 @@ static int pci_esp_probe_one(struct pci_dev *pdev,
          * DMA for command submission.
          */
         esp->flags |= ESP_FLAG_USE_FIFO;
+        /*
+         * Enable CONFIG2_FENAB to allow for large DMA transfers
+         */
+        if (am53c974_fenab)
+                esp->config2 |= ESP_CONFIG2_FENAB;
+
         pep->esp = esp;
 
         if (pci_request_regions(pdev, DRV_MODULE_NAME)) {
@@ -541,5 +578,8 @@ MODULE_VERSION(DRV_MODULE_VERSION);
 module_param(am53c974_debug, bool, 0644);
 MODULE_PARM_DESC(am53c974_debug, "Enable debugging");
 
+module_param(am53c974_fenab, bool, 0444);
+MODULE_PARM_DESC(am53c974_fenab, "Enable 24-bit DMA transfer sizes");
+
 module_init(am53c974_module_init);
 module_exit(am53c974_module_exit);
diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 8ea03af435ba..ce5bd52fe692 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c
@@ -1343,6 +1343,8 @@ 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;