linux-kernel - Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

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Date:   Mon, 15 Oct 2018 07:54:28 +0200
From:   Hannes Reinecke <hare@...e.de>
To:     Finn Thain <fthain@...egraphics.com.au>,
        "James E.J. Bottomley" <jejb@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     Michael Schmitz <schmitzmic@...il.com>, linux-scsi@...r.kernel.org,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] esp_scsi: De-duplicate PIO routines

On 10/13/18 2:51 AM, Finn Thain wrote:
> As a temporary measure, the code to implement PIO transfers was
> duplicated in zorro_esp and mac_esp. Now that this code has stabilized,
> move it into the core driver to eliminate the duplication.
> 
> This replaces the inline assembler with more portable writesb() calls.
> Optimizing the m68k writesb() implementation is a separate patch.
> 
> Tested-by: Stan Johnson <userm57@...oo.com>
> Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
> ---
>   drivers/scsi/esp_scsi.c  | 126 +++++++++++++++++++++++++
>   drivers/scsi/esp_scsi.h  |   5 +
>   drivers/scsi/mac_esp.c   | 173 ++---------------------------------
>   drivers/scsi/zorro_esp.c | 232 +++++++----------------------------------------
>   4 files changed, 171 insertions(+), 365 deletions(-)
> 
> diff --git a/drivers/scsi/esp_scsi.c b/drivers/scsi/esp_scsi.c
> index 6ccaf818357e..646701fc22a4 100644
> --- a/drivers/scsi/esp_scsi.c
> +++ b/drivers/scsi/esp_scsi.c
> @@ -2776,3 +2776,129 @@ MODULE_PARM_DESC(esp_debug,
>   
>   module_init(esp_init);
>   module_exit(esp_exit);
> +
> +#if IS_ENABLED(CONFIG_SCSI_MAC_ESP) || IS_ENABLED(CONFIG_SCSI_ZORRO_ESP)
> +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);
> +
> +	pr_err("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);
> +
> +	pr_err("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

These function are conditional, but

> 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) */
These are not.

Which will result in building errors when the said configuration is not 
enabled.
Please fix by either making everything conditional or remove the 
conditional completely.

Cheers,

Hannes
-- 
Dr. Hannes Reinecke		   Teamlead Storage & Networking
hare@...e.de			               +49 911 74053 688
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