Hello,
> Add "em_buffer" attribute for SATA AHCI hosts to enable user access
> AHCI EM (enclosure management) buffer in user space if the host
> support EM.
>
> AHCI driver should support SGPIO EM message. However the SATA/AHCI
> spec does no define the SGPIO message format filled in EM
> buffer. Different HW vendors may have different definitions. The
> mainly purpose of "em_buffer" attribute is to solve this issue by
> allowing HW vendors to provide user space SGPIO drivers and tools.
Yeap, the only way to deal with the SGPIO case seems to be to provide
a way for userland to directly generate and consume messages.
> @@ -931,18 +937,20 @@ static ssize_t ahci_transmit_led_message(struct ata_port *ap, u32 state,
> return -EBUSY;
> }
>
> - /*
> - * create message header - this is all zero except for
> - * the message size, which is 4 bytes.
> - */
> - message[0] |= (4 << 8);
> + if (ahci_em_messages & 0x01) {
> + /*
> + * create message header - this is all zero except for
> + * the message size, which is 4 bytes.
> + */
> + message[0] |= (4 << 8);
This isn't your fault but there can be multiple ahci controllers on
the system and controlling EM capability via a module parameter
doesn't really work. There needs to be some mechanism to configure
this automatically.
> +static ssize_t ahci_em_buffer_store(struct ata_port *ap,
> + const char *buf, size_t size)
> +{
> + struct ahci_host_priv *hpriv = ap->host->private_data;
> + void __iomem *mmio = hpriv->mmio;
> + void __iomem *em_mmio = mmio + hpriv->em_loc;
> + struct ahci_em_buf_msg *msg = (struct ahci_em_buf_msg *)buf;
> + u32 em_ctl;
> + unsigned long flags;
> + int i, tmp;
> +
> + /* check message validity */
> + tmp = sizeof(struct ahci_em_buf_msg);
> + if (size % 4 || size < tmp || size > tmp + msg->len * 4 ||
> + msg->start + msg->len > hpriv->em_buf_sz / 4) {
> + return -EINVAL;
> + }
Please don't share data structure directly with userland this way.
The action of storing can indicate TM. I don't think RST needs to be
exported to userland verbatim. @start is unnecessary if the whole
message is written always and @len can be determined from the write
size. IOW, simply writing the raw message should be enough.
Also, isn't it also necessary to implement 'read'?
> +static ssize_t
> +ata_scsi_em_buffer_store(struct device *dev, struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct Scsi_Host *shost = class_to_shost(dev);
> + struct ata_port *ap = ata_shost_to_port(shost);
> +
> + if (ap->ops->em_buffer_store && (ap->flags & ATA_FLAG_EM))
> + return ap->ops->em_buffer_store(ap, buf, count);
> + return -EINVAL;
> +}
> +DEVICE_ATTR(em_buffer, S_IWUSR, NULL, ata_scsi_em_buffer_store);
> +EXPORT_SYMBOL_GPL(dev_attr_em_buffer);
Let's just put it in libahci.c for now and move it to common part if
anything else ever requires SGPIO EM.
Thanks.
--
tejun
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