As a temporary measure, the code to implement PIO transfers was
duplicated in zorro_esp and mac_esp. Now that it has stabilized
move the common code into the core driver but don't build it unless
needed.

This replaces the inline assembler with more portable writesb() calls.
Optimizing the m68k writesb() implementation is a separate patch.

Tested-by: Stan Johnson <redacted>
Signed-off-by: Finn Thain <redacted>
Tested-by: Michael Schmitz <schmitzmic@gmail.com>
---
Changed since v1:
  - Use shost_printk() instead of pr_err().
  - Add new symbol CONFIG_SCSI_ESP_PIO to Kconfig.
---
  drivers/scsi/Kconfig     |   6 +
  drivers/scsi/esp_scsi.c  | 128 +++++++++++++++++++++
  drivers/scsi/esp_scsi.h  |   5 +
  drivers/scsi/mac_esp.c   | 173 +----------------------------
  drivers/scsi/zorro_esp.c | 232 ++++++---------------------------------
  5 files changed, 179 insertions(+), 365 deletions(-)

diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 35c909bbf8ba..81c6872f24f8 100644
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig

@@ -42,6 +42,10 @@ config SCSI_DMA
  	bool
  	default n
  
+config SCSI_ESP_PIO
+	bool
+	default n
+
  config SCSI_NETLINK
  	bool
  	default	n

@@ -1355,6 +1359,7 @@ config SCSI_ZORRO_ESP
  	tristate "Zorro ESP SCSI support"
  	depends on ZORRO && SCSI
  	select SCSI_SPI_ATTRS
+	select SCSI_ESP_PIO
  	help
  	  Support for various NCR53C9x (ESP) based SCSI controllers on Zorro
  	  expansion boards for the Amiga.

@@ -1397,6 +1402,7 @@ config SCSI_MAC_ESP
  	tristate "Macintosh NCR53c9[46] SCSI"
  	depends on MAC && SCSI
  	select SCSI_SPI_ATTRS
+	select SCSI_ESP_PIO
  	help
  	  This is the NCR 53c9x SCSI controller found on most of the 68040
  	  based Macintoshes.

diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
index 6ccaf818357e..305a322ad13c 100644
--- a/drivers/scsi/esp_scsi.c
+++ b/drivers/scsi/esp_scsi.c

@@ -2776,3 +2776,131 @@ MODULE_PARM_DESC(esp_debug,
  
  module_init(esp_init);
  module_exit(esp_exit);
+
+#ifdef CONFIG_SCSI_ESP_PIO
+static inline unsigned int esp_wait_for_fifo(struct esp *esp)
+{
+	int i = 500000;
+
+	do {
+		unsigned int fbytes = esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES;
+
+		if (fbytes)
+			return fbytes;
+
+		udelay(2);
+	} while (--i);
+
+	shost_printk(KERN_ERR, esp->host, "FIFO is empty (sreg %02x)\n",
+		     esp_read8(ESP_STATUS));
+	return 0;
+}
+
+static inline int esp_wait_for_intr(struct esp *esp)
+{
+	int i = 500000;
+
+	do {
+		esp->sreg = esp_read8(ESP_STATUS);
+		if (esp->sreg & ESP_STAT_INTR)
+			return 0;
+
+		udelay(2);
+	} while (--i);
+
+	shost_printk(KERN_ERR, esp->host, "IRQ timeout (sreg %02x)\n",
+		     esp->sreg);
+	return 1;
+}
+
+#define ESP_FIFO_SIZE 16
+
+void esp_send_pio_cmd(struct esp *esp, u32 addr, u32 esp_count,
+		      u32 dma_count, int write, u8 cmd)
+{
+	u8 phase = esp->sreg & ESP_STAT_PMASK;
+
+	cmd &= ~ESP_CMD_DMA;
+	esp->send_cmd_error = 0;
+
+	if (write) {
+		u8 *dst = (u8 *)addr;
+		u8 mask = ~(phase == ESP_MIP ? ESP_INTR_FDONE : ESP_INTR_BSERV);
+
+		scsi_esp_cmd(esp, cmd);
+
+		while (1) {
+			if (!esp_wait_for_fifo(esp))
+				break;
+
+			*dst++ = esp_read8(ESP_FDATA);
+			--esp_count;
+
+			if (!esp_count)
+				break;
+
+			if (esp_wait_for_intr(esp)) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if ((esp->sreg & ESP_STAT_PMASK) != phase)
+				break;
+
+			esp->ireg = esp_read8(ESP_INTRPT);
+			if (esp->ireg & mask) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if (phase == ESP_MIP)
+				scsi_esp_cmd(esp, ESP_CMD_MOK);
+
+			scsi_esp_cmd(esp, ESP_CMD_TI);
+		}
+	} else {
+		unsigned int n = ESP_FIFO_SIZE;
+		u8 *src = (u8 *)addr;
+
+		scsi_esp_cmd(esp, ESP_CMD_FLUSH);
+
+		if (n > esp_count)
+			n = esp_count;
+		writesb(esp->fifo_reg, src, n);
+		src += n;
+		esp_count -= n;
+
+		scsi_esp_cmd(esp, cmd);
+
+		while (esp_count) {
+			if (esp_wait_for_intr(esp)) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			if ((esp->sreg & ESP_STAT_PMASK) != phase)
+				break;
+
+			esp->ireg = esp_read8(ESP_INTRPT);
+			if (esp->ireg & ~ESP_INTR_BSERV) {
+				esp->send_cmd_error = 1;
+				break;
+			}
+
+			n = ESP_FIFO_SIZE -
+			    (esp_read8(ESP_FFLAGS) & ESP_FF_FBYTES);
+
+			if (n > esp_count)
+				n = esp_count;
+			writesb(esp->fifo_reg, src, n);
+			src += n;
+			esp_count -= n;
+
+			scsi_esp_cmd(esp, ESP_CMD_TI);
+		}
+	}
+
+	esp->send_cmd_residual = esp_count;
+}
+EXPORT_SYMBOL(esp_send_pio_cmd);
+#endif

diff --git a/drivers/scsi/esp_scsi.h b/drivers/scsi/esp_scsi.h
index d0c032803749..2590e5eda595 100644
--- a/drivers/scsi/esp_scsi.h
+++ b/drivers/scsi/esp_scsi.h

@@ -431,6 +431,7 @@ struct esp_driver_ops {
  struct esp {
  	void __iomem		*regs;
  	void __iomem		*dma_regs;
+	u8 __iomem		*fifo_reg;
  
  	const struct esp_driver_ops *ops;
  

@@ -540,6 +541,7 @@ struct esp {
  	void			*dma;
  	int			dmarev;
  
+	int			send_cmd_error;
  	int			send_cmd_residual;
  };
  

@@ -581,4 +583,7 @@ extern void scsi_esp_unregister(struct esp *);
  extern irqreturn_t scsi_esp_intr(int, void *);
  extern void scsi_esp_cmd(struct esp *, u8);
  
+extern void esp_send_pio_cmd(struct esp *esp, u32 dma_addr, u32 esp_count,
+			     u32 dma_count, int write, u8 cmd);
+
  #endif /* !(_ESP_SCSI_H) */