SCSI: Make SPI transport attributes mutable

This adds the final missing piece to the transport attributes:  A
published API by which they can be set and retrieved (SPI attributes
only).  The sysfs field only appears writeable if the driver supplied a
set method in the attribute template, so unsettable attributes show up
as read only.

The consequence now is that the spi transport attribute class is no
longer a simple exported structure: the driver has to attach to the spi
transport class at module initialisation.

drivers/scsi/scsi_transport_spi.c

@@ -26,6 +26,41 @@
 
 static void transport_class_release(struct class_device *class_dev);
 
+#define SPI_NUM_ATTRS 10	/* increase this if you add attributes */
+
+struct spi_internal {
+	struct scsi_transport_template t;
+	struct spi_function_template *f;
+	/* The actual attributes */
+	struct class_device_attribute private_attrs[SPI_NUM_ATTRS];
+	/* The array of null terminated pointers to attributes 
+	 * needed by scsi_sysfs.c */
+	struct class_device_attribute *attrs[SPI_NUM_ATTRS + 1];
+};
+
+#define to_spi_internal(tmpl)	container_of(tmpl, struct spi_internal, t)
+
+static const char *const ppr_to_ns[] = {
+	/* The PPR values 0-6 are reserved, fill them in when
+	 * the committee defines them */
+	NULL,			/* 0x00 */
+	NULL,			/* 0x01 */
+	NULL,			/* 0x02 */
+	NULL,			/* 0x03 */
+	NULL,			/* 0x04 */
+	NULL,			/* 0x05 */
+	NULL,			/* 0x06 */
+	"3.125",		/* 0x07 */
+	"6.25",			/* 0x08 */
+	"12.5",			/* 0x09 */
+	"25",			/* 0x0a */
+	"30.3",			/* 0x0b */
+	"50",			/* 0x0c */
+};
+/* The PPR values at which you calculate the period in ns by multiplying
+ * by 4 */
+#define SPI_STATIC_PPR	0x0c
+
 struct class spi_transport_class = {
 	.name = "spi_transport",
 	.release = transport_class_release,
@@ -63,19 +98,40 @@ static void transport_class_release(struct class_device *class_dev)
 	put_device(&sdev->sdev_gendev);
 }
 
-#define spi_transport_show_function(field, format_string)			\
-static ssize_t									\
-show_spi_transport_##field (struct class_device *cdev, char *buf)		\
-{										\
-	struct scsi_device *sdev = transport_class_to_sdev(cdev);		\
-	struct spi_transport_attrs *tp;						\
-	tp = (struct spi_transport_attrs *)&sdev->transport_data;		\
-	return snprintf(buf, 20, format_string, tp->field);			\
+#define spi_transport_show_function(field, format_string)		\
+									\
+static ssize_t								\
+show_spi_transport_##field(struct class_device *cdev, char *buf)	\
+{									\
+	struct scsi_device *sdev = transport_class_to_sdev(cdev);	\
+	struct spi_transport_attrs *tp;					\
+	struct spi_internal *i = to_spi_internal(sdev->host->transportt); \
+	tp = (struct spi_transport_attrs *)&sdev->transport_data;	\
+	if(i->f->get_##field)						\
+		i->f->get_##field(sdev);				\
+	return snprintf(buf, 20, format_string, tp->field);		\
+}
+
+#define spi_transport_store_function(field, format_string)		\
+static ssize_t								\
+store_spi_transport_##field(struct class_device *cdev, const char *buf, \
+			    size_t count)				\
+{									\
+	int val;							\
+	struct scsi_device *sdev = transport_class_to_sdev(cdev);	\
+	struct spi_internal *i = to_spi_internal(sdev->host->transportt); \
+									\
+	val = simple_strtoul(buf, NULL, 0);				\
+	i->f->set_##field(sdev, val);					\
+	return count;							\
 }
 
-#define spi_transport_rd_attr(field, format_string)				\
-	spi_transport_show_function(field, format_string)			\
-static CLASS_DEVICE_ATTR( field, S_IRUGO, show_spi_transport_##field, NULL)
+#define spi_transport_rd_attr(field, format_string)			\
+	spi_transport_show_function(field, format_string)		\
+	spi_transport_store_function(field, format_string)		\
+static CLASS_DEVICE_ATTR(field, S_IRUGO | S_IWUSR,			\
+			 show_spi_transport_##field,			\
+			 store_spi_transport_##field)
 
 /* The Parallel SCSI Tranport Attributes: */
 spi_transport_rd_attr(offset, "%d\n");
@@ -95,72 +151,148 @@ static ssize_t show_spi_transport_period(struct class_device *cdev, char *buf)
 {
 	struct scsi_device *sdev = transport_class_to_sdev(cdev);
 	struct spi_transport_attrs *tp;
-	char *str;
+	const char *str;
+	struct spi_internal *i = to_spi_internal(sdev->host->transportt);
 
 	tp = (struct spi_transport_attrs *)&sdev->transport_data;
 
+	if(i->f->get_period)
+		i->f->get_period(sdev);
+
 	switch(tp->period) {
-	case 0x00 ... 0x06:
-		str =  "reserved";
-		break;
 
-	case 0x07:
-		str = "3.125";
+	case 0x07 ... SPI_STATIC_PPR:
+		str = ppr_to_ns[tp->period];
+		if(!str)
+			str = "reserved";
 		break;
 
-	case 0x08:
-		str = "6.25";
-		break;
 
-	case 0x09:
-		str = "12.5";
-		break;
+	case (SPI_STATIC_PPR+1) ... 0xff:
+		return sprintf(buf, "%d\n", tp->period * 4);
 
-	case 0x0a:
-		str = "25";
-		break;
+	default:
+		str = "unknown";
+	}
+	return sprintf(buf, "%s\n", str);
+}
 
-	case 0x0b:
-		str = "30.3";
+static ssize_t
+store_spi_transport_period(struct class_device *cdev, const char *buf,
+			    size_t count)
+{
+	struct scsi_device *sdev = transport_class_to_sdev(cdev);
+	struct spi_internal *i = to_spi_internal(sdev->host->transportt);
+	int j, period = -1;
+
+	for(j = 0; j < SPI_STATIC_PPR; j++) {
+		int len;
+
+		if(ppr_to_ns[j] == NULL)
+			continue;
+
+		len = strlen(ppr_to_ns[j]);
+
+		if(strncmp(ppr_to_ns[j], buf, len) != 0)
+			continue;
+
+		if(buf[len] != '\n')
+			continue;
+		
+		period = j;
 		break;
+	}
 
-	case 0x0c:
-		str = "50";
+	if(period == -1) {
+		 int val = simple_strtoul(buf, NULL, 0);
 
-	case 0x0d ... 0xff:
-		return sprintf(buf, "%d\n", tp->period * 4);
+		 
+		 if(val >= (SPI_STATIC_PPR + 1)*4)
+			  period = val/4;
 
-	default:
-		str = "unknown";
 	}
-	return sprintf(buf, "%s\n", str);
+
+	if(period == -1 || period > 0xff)
+		 return -EINVAL;
+
+	i->f->set_period(sdev, period);
+
+	return count;
 }
+	
+
+	
+		 
+
+
+static CLASS_DEVICE_ATTR(period, S_IRUGO | S_IWUSR, 
+			 show_spi_transport_period,
+			 store_spi_transport_period);
 
-static CLASS_DEVICE_ATTR(period, S_IRUGO, show_spi_transport_period, NULL);
-
-
-struct class_device_attribute *spi_transport_attrs[] = {
-	&class_device_attr_period,
-	&class_device_attr_offset,
-	&class_device_attr_width,
-	&class_device_attr_iu,
-	&class_device_attr_dt,
-	&class_device_attr_qas,
-	&class_device_attr_wr_flow,
-	&class_device_attr_rd_strm,
-	&class_device_attr_rti,
-	&class_device_attr_pcomp_en,
-	NULL
-};
 
 struct scsi_transport_template spi_transport_template = {
-	.attrs = spi_transport_attrs,
 	.class = &spi_transport_class,
 	.setup = &spi_setup_transport_attrs,
 	.cleanup = NULL,
 	.size = sizeof(struct spi_transport_attrs) - sizeof(unsigned long),
 };
-EXPORT_SYMBOL(spi_transport_template);
+
+#define SETUP_ATTRIBUTE(field)						\
+	i->private_attrs[count] = class_device_attr_##field;		\
+	if(!i->f->set_##field) {					\
+		i->private_attrs[count].attr.mode = S_IRUGO;		\
+		i->private_attrs[count].store = NULL;			\
+	}								\
+	i->attrs[count] = &i->private_attrs[count];			\
+	count++
+
+struct scsi_transport_template *
+spi_attach_transport(struct spi_function_template *ft)
+{
+	struct spi_internal *i = kmalloc(sizeof(struct spi_internal),
+					 GFP_KERNEL);
+	int count = 0;
+	if(!i)
+		return NULL;
+
+	memset(i, 0, sizeof(struct spi_internal));
+
+
+	i->t.attrs = &i->attrs[0];
+	i->t.class = &spi_transport_class;
+	i->t.setup = &spi_setup_transport_attrs;
+	i->t.size = sizeof(struct spi_transport_attrs) - sizeof(unsigned long);
+	i->f = ft;
+
+	SETUP_ATTRIBUTE(period);
+	SETUP_ATTRIBUTE(offset);
+	SETUP_ATTRIBUTE(width);
+	SETUP_ATTRIBUTE(iu);
+	SETUP_ATTRIBUTE(dt);
+	SETUP_ATTRIBUTE(qas);
+	SETUP_ATTRIBUTE(wr_flow);
+	SETUP_ATTRIBUTE(rd_strm);
+	SETUP_ATTRIBUTE(rti);
+	SETUP_ATTRIBUTE(pcomp_en);
+
+	/* if you add an attribute but forget to increase SPI_NUM_ATTRS
+	 * this bug will trigger */
+	BUG_ON(count != SPI_NUM_ATTRS);
+
+	i->attrs[count] = NULL;
+
+	return &i->t;
+}
+EXPORT_SYMBOL(spi_attach_transport);
+
+void spi_release_transport(struct scsi_transport_template *t)
+{
+	struct spi_internal *i = to_spi_internal(t);
+
+	kfree(i);
+}
+EXPORT_SYMBOL(spi_release_transport);
+
 
 MODULE_AUTHOR("Martin Hicks");
 MODULE_DESCRIPTION("SPI Transport Attributes");

include/scsi/scsi_transport_spi.h

@@ -48,6 +48,32 @@ struct spi_transport_attrs {
 #define spi_rd_strm(x)	(((struct spi_transport_attrs *)&(x)->transport_data)->rd_strm)
 #define spi_rti(x)	(((struct spi_transport_attrs *)&(x)->transport_data)->rti)
 #define spi_pcomp_en(x)	(((struct spi_transport_attrs *)&(x)->transport_data)->pcomp_en)
-extern struct scsi_transport_template spi_transport_template;
+
+/* The functions by which the transport class and the driver communicate */
+struct spi_function_template {
+	void	(*get_period)(struct scsi_device *);
+	void	(*set_period)(struct scsi_device *, int);
+	void	(*get_offset)(struct scsi_device *);
+	void	(*set_offset)(struct scsi_device *, int);
+	void	(*get_width)(struct scsi_device *);
+	void	(*set_width)(struct scsi_device *, int);
+	void	(*get_iu)(struct scsi_device *);
+	void	(*set_iu)(struct scsi_device *, int);
+	void	(*get_dt)(struct scsi_device *);
+	void	(*set_dt)(struct scsi_device *, int);
+	void	(*get_qas)(struct scsi_device *);
+	void	(*set_qas)(struct scsi_device *, int);
+	void	(*get_wr_flow)(struct scsi_device *);
+	void	(*set_wr_flow)(struct scsi_device *, int);
+	void	(*get_rd_strm)(struct scsi_device *);
+	void	(*set_rd_strm)(struct scsi_device *, int);
+	void	(*get_rti)(struct scsi_device *);
+	void	(*set_rti)(struct scsi_device *, int);
+	void	(*get_pcomp_en)(struct scsi_device *);
+	void	(*set_pcomp_en)(struct scsi_device *, int);
+};
+
+struct scsi_transport_template *spi_attach_transport(struct spi_function_template *);
+void spi_release_transport(struct scsi_transport_template *);
 
 #endif /* SCSI_TRANSPORT_SPI_H */