[RFC v1 5/6] crypto/ccp: Register with fw_uploader and always fail

[Tycho Andersen <tycho@kernel.org>]

From: "Tycho Andersen (AMD)" <tycho@kernel.org>

In preparation for SNP live firmware downloading support, add an 'sev'
firmware loader that always fails with EBUSY.

Signed-off-by: Tycho Andersen (AMD) <tycho@kernel.org>
---
 drivers/crypto/ccp/sev-dev.c | 51 ++++++++++++++++++++++++++++++++++++
 drivers/crypto/ccp/sev-dev.h |  3 +++
 2 files changed, 54 insertions(+)

diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c
index 2df621b9f6e2..b4711bf823e8 100644
--- a/drivers/crypto/ccp/sev-dev.c
+++ b/drivers/crypto/ccp/sev-dev.c
@@ -2040,6 +2040,53 @@ static int sev_update_firmware(struct device *dev)
 	return ret;
 }
 
+static enum fw_upload_err sev_fw_upload_prepare(struct fw_upload *fw_upload,
+						const u8 *data, u32 size)
+{
+	return FW_UPLOAD_ERR_NONE;
+}
+
+static enum fw_upload_err sev_fw_upload_write(struct fw_upload *fw_upload,
+					      const u8 *data, u32 offset,
+					      u32 size, u32 *written)
+{
+	return FW_UPLOAD_ERR_BUSY;
+}
+
+static enum fw_upload_err sev_fw_upload_poll_complete(struct fw_upload *fw_upload)
+{
+	return FW_UPLOAD_ERR_NONE;
+}
+
+static void sev_fw_upload_cancel(struct fw_upload *fw_upload)
+{
+	/* intentional no-op */
+}
+
+static const struct fw_upload_ops sev_fw_upload_ops = {
+	.prepare = sev_fw_upload_prepare,
+	.write = sev_fw_upload_write,
+	.poll_complete = sev_fw_upload_poll_complete,
+	.cancel = sev_fw_upload_cancel,
+};
+
+static void register_sev_fw_uploader(struct sev_device *sev)
+{
+	struct fw_upload *fwl;
+
+	if (!IS_ENABLED(CONFIG_FW_UPLOAD))
+		return;
+
+	fwl = firmware_upload_register(THIS_MODULE, sev->dev, "sev",
+				       &sev_fw_upload_ops, sev);
+	if (IS_ERR(fwl)) {
+		dev_err(sev->dev, "SEV firmware upload registration failure: %ld\n", PTR_ERR(fwl));
+		return;
+	}
+
+	sev->fwl = fwl;
+}
+
 static int __sev_snp_shutdown_locked(int *error, bool panic)
 {
 	struct psp_device *psp = psp_master;
@@ -2953,6 +3000,7 @@ void sev_pci_init(void)
 			 api_major, api_minor, build,
 			 sev->api_major, sev->api_minor, sev->build);
 
+	register_sev_fw_uploader(sev);
 	return;
 
 err:
@@ -2969,4 +3017,7 @@ void sev_pci_exit(void)
 		return;
 
 	sev_firmware_shutdown(sev);
+
+	if (sev->fwl)
+		firmware_upload_unregister(sev->fwl);
 }
diff --git a/drivers/crypto/ccp/sev-dev.h b/drivers/crypto/ccp/sev-dev.h
index b1cd556bbbf6..2f5781cb7bb1 100644
--- a/drivers/crypto/ccp/sev-dev.h
+++ b/drivers/crypto/ccp/sev-dev.h
@@ -24,6 +24,7 @@
 #include <linux/psp-sev.h>
 #include <linux/miscdevice.h>
 #include <linux/capability.h>
+#include <linux/firmware.h>
 
 #define SEV_CMDRESP_CMD			GENMASK(26, 16)
 #define SEV_CMD_COMPLETE		BIT(1)
@@ -66,6 +67,8 @@ struct sev_device {
 
 	struct tsm_dev *tsmdev;
 	struct sev_tio_status *tio_status;
+
+	struct fw_upload *fwl;
 };
 
 int sev_dev_init(struct psp_device *psp);
-- 
2.54.0