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Message-ID: <57472450.4000709@arm.com>
Date: Thu, 26 May 2016 17:29:04 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Neil Armstrong <narmstrong@...libre.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
Sudeep Holla <sudeep.holla@....com>
Subject: Re: [RFC PATCH 0/2] scpi: Add SCPI framework to handle vendors
variants
Hi Neil,
On 26/05/16 10:38, Neil Armstrong wrote:
> Since the current SCPI implementation, based on [0]:
> - is (at leat) JUNO specific
Agreed.
> - does not specify a strong "standard"
Not exactly, it's extensible. Refer section 3.2.2. Get SCP capability
Extended Set Enabled bit.
> - does not specify a strong MHU interface specification
>
Not really required, any mailbox must do.
> SoC vendors could implement a variant with slight changes in message
> indexes,
I assume you mean command index here
> new messages types,
Also fine with extended command set.
> different messages data format or
you mean the header or payload ? If they don't follow the header, then
how can be group them as same protocol ?
> different MHU communication scheme.
Not a problem as I mentioned above.
>
> To keep the spirit of the SCPI interface, add a thin "register" layer to get
> the ops from the parent node and switch the drivers using the ops to use
> the new of_scpi_ops_get() call.
>
All I can see is that you share the code to register such drivers which
is hardly anything. It's hard to say all drivers use same protocol or
interface after this change. I may be missing to see something here so
it would be easy to appreciate/review this change with one user of this.
My idea of extending this driver if vendor implements extensions based
on SCPI specification is something like below:
--
Regards,
Sudeep
-->8
diff --git i/drivers/firmware/arm_scpi.c w/drivers/firmware/arm_scpi.c
index 7e3e595c9f30..7e46aa103690 100644
--- i/drivers/firmware/arm_scpi.c
+++ w/drivers/firmware/arm_scpi.c
@@ -46,6 +46,8 @@
#define CMD_ID_SHIFT 0
#define CMD_ID_MASK 0x7f
+#define CMD_SET_SHIFT 7
+#define CMD_SET_MASK 0x1
#define CMD_TOKEN_ID_SHIFT 8
#define CMD_TOKEN_ID_MASK 0xff
#define CMD_DATA_SIZE_SHIFT 16
@@ -53,6 +55,10 @@
#define PACK_SCPI_CMD(cmd_id, tx_sz) \
((((cmd_id) & CMD_ID_MASK) << CMD_ID_SHIFT) | \
(((tx_sz) & CMD_DATA_SIZE_MASK) << CMD_DATA_SIZE_SHIFT))
+#define PACK_EXT_SCPI_CMD(cmd_id, tx_sz) \
+ ((((cmd_id) & CMD_ID_MASK) << CMD_ID_SHIFT) | \
+ (CMD_SET_MASK << CMD_SET_SHIFT) | \
+ (((tx_sz) & CMD_DATA_SIZE_MASK) << CMD_DATA_SIZE_SHIFT))
#define ADD_SCPI_TOKEN(cmd, token) \
((cmd) |= (((token) & CMD_TOKEN_ID_MASK) << CMD_TOKEN_ID_SHIFT))
@@ -132,6 +138,9 @@ enum scpi_std_cmd {
SCPI_CMD_COUNT
};
+enum scpi_vendor_ext_cmd {
+};
+
struct scpi_xfer {
u32 slot; /* has to be first element */
u32 cmd;
@@ -165,6 +174,7 @@ struct scpi_drvinfo {
struct scpi_ops *scpi_ops;
struct scpi_chan *channels;
struct scpi_dvfs_info *dvfs[MAX_DVFS_DOMAINS];
+ void *scpi_ext_ops;
};
/*
@@ -343,8 +353,8 @@ static void put_scpi_xfer(struct scpi_xfer *t,
struct scpi_chan *ch)
mutex_unlock(&ch->xfers_lock);
}
-static int scpi_send_message(u8 cmd, void *tx_buf, unsigned int tx_len,
- void *rx_buf, unsigned int rx_len)
+static int __scpi_send_message(u8 cmd, void *tx_buf, unsigned int tx_len,
+ void *rx_buf, unsigned int rx_len, bool extn)
{
int ret;
u8 chan;
@@ -359,7 +369,8 @@ static int scpi_send_message(u8 cmd, void *tx_buf,
unsigned int tx_len,
return -ENOMEM;
msg->slot = BIT(SCPI_SLOT);
- msg->cmd = PACK_SCPI_CMD(cmd, tx_len);
+ msg->cmd = extn ? PACK_EXT_SCPI_CMD(cmd, tx_len) :
+ PACK_SCPI_CMD(cmd, tx_len);
msg->tx_buf = tx_buf;
msg->tx_len = tx_len;
msg->rx_buf = rx_buf;
@@ -384,6 +395,18 @@ static int scpi_send_message(u8 cmd, void *tx_buf,
unsigned int tx_len,
return ret > 0 ? scpi_to_linux_errno(ret) : ret;
}
+static int scpi_send_message(u8 cmd, void *tx_buf, unsigned int tx_len,
+ void *rx_buf, unsigned int rx_len)
+{
+ return __scpi_send_message(cmd, tx_buf, tx_len, rx_buf, rx_len, false);
+}
+
+static int scpi_send_ext_message(u8 cmd, void *tx_buf, unsigned int tx_len,
+ void *rx_buf, unsigned int rx_len)
+{
+ return __scpi_send_message(cmd, tx_buf, tx_len, rx_buf, rx_len, true);
+}
+
static u32 scpi_get_version(void)
{
return scpi_info->protocol_version;
@@ -574,6 +597,29 @@ static int scpi_init_versions(struct scpi_drvinfo
*info)
return ret;
}
+static struct scpi_vendor_ext_ops scpi_vendor_ext_ops = {
+};
+
+void *get_scpi_ext_ops(void)
+{
+ return scpi_info ? scpi_info->scpi_ext_ops : NULL;
+}
+EXPORT_SYMBOL_GPL(get_scpi_ext_ops);
+
+static const struct of_device_id scpi_extentions_of_match[] = {
+ {.compatible = "vendor,scpi", .data = &scpi_vendor_ext_ops},
+ {},
+};
+
+static void
+scpi_init_extensions(struct scpi_drvinfo *info, struct device_node *np)
+{
+ const struct of_device_id *of_id;
+
+ if (np && (of_id = of_match_node(scpi_extentions_of_match, np)))
+ info->scpi_ext_ops = (void *)of_id->data;
+}
+
static ssize_t protocol_version_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
@@ -745,6 +791,8 @@ static int scpi_probe(struct platform_device *pdev)
FW_REV_PATCH(scpi_info->firmware_version));
scpi_info->scpi_ops = &scpi_ops;
+ scpi_init_extensions(scpi_info, np);
+
ret = sysfs_create_groups(&dev->kobj, versions_groups);
if (ret)
dev_err(dev, "unable to create sysfs version group\n");
diff --git i/include/linux/scpi_protocol.h w/include/linux/scpi_protocol.h
index 35de50a65665..052f6aa1ae4b 100644
--- i/include/linux/scpi_protocol.h
+++ w/include/linux/scpi_protocol.h
@@ -72,8 +72,13 @@ struct scpi_ops {
int (*sensor_get_value)(u16, u64 *);
};
+struct scpi_vendor_ext_ops {
+};
+
#if IS_REACHABLE(CONFIG_ARM_SCPI_PROTOCOL)
struct scpi_ops *get_scpi_ops(void);
+void *get_scpi_ext_ops(void);
#else
static inline struct scpi_ops *get_scpi_ops(void) { return NULL; }
+static inline void *get_scpi_ext_ops(void) { return NULL; }
#endif
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