drivers/qcom: add Command DB support

Changes since v7:
- Add reviewed-by tags
- Fix example

Changes since v6:
- Fix 'reg' property
- Add reviewed-by tags

Changes since v5:
- Remove indirection of command db start address
- Rebase on top of 4.16

Changes since v4:
- Address comments from Stephen and Bjorn

These patches add support for reading a shared memory database in the newer QCOM SoCs called Command DB. With the new architecture on SDM845, shared resources like clocks, regulators etc., have dynamic properties. These properties may change based on external components, board configurations or available feature set. A remote processor detects these parameters and fills up the database with the resource and available state information. Platform drivers that need these shared resources will need to query this database to get the address and properties and vote for the state.

The information in the database is static. The database is read-only memory location that is available for Linux. A pre-defined string is used as a key into an entry in the database. Generally, platform drivers query the database only at init to get the information they need.

[v1]: https://www.spinics.net/lists/linux-arm-msm/msg32462.html
[v2]: https://lkml.org/lkml/2018/2/8/588
[v3]: https://lkml.org/lkml/2018/2/16/842
[v4]: https://patchwork.kernel.org/patch/10242935/
[v5]: https://lkml.org/lkml/2018/3/14/787
[v6]: https://lkml.org/lkml/2018/4/5/451
[v7]: https://lkml.org/lkml/2018/4/6/756

Lina Iyer (2):
drivers: qcom: add command DB driver
dt-bindings: introduce Command DB for QCOM SoCs

 .../bindings/reserved-memory/qcom,cmd-db.txt       |  37 +++
 drivers/of/platform.c                              |   1 +
 drivers/soc/qcom/Kconfig                           |   9 +
 drivers/soc/qcom/Makefile                          |   1 +
 drivers/soc/qcom/cmd-db.c                          | 310 +++++++++++++++++++++
 include/soc/qcom/cmd-db.h                          |  45 +++
 6 files changed, 403 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/qcom,cmd-db.txt
 create mode 100644 drivers/soc/qcom/cmd-db.c
 create mode 100644 include/soc/qcom/cmd-db.h

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project

From: Mahesh Sivasubramanian <[email protected]>

Command DB is a simple database in the shared memory of QCOM SoCs, that provides information regarding shared resources. Some shared resources in the SoC have properties that are probed dynamically at boot by the remote processor. The information pertaining to the SoC and the platform are made available in the shared memory. Drivers can query this information using predefined strings.

---

Changes in v6:
- Remove indirection and use the actual command db memory in DT

Changes in v5:
- Use strncmp
- Add check in probe to ensure the location at dictionary address is same as the one specified in reserved-memory
- Whitespace fixes
- Comments updated

---
 drivers/of/platform.c     |   1 +
 drivers/soc/qcom/Kconfig  |   9 ++
 drivers/soc/qcom/Makefile |   1 +
 drivers/soc/qcom/cmd-db.c | 310 ++++++++++++++++++++++++++++++++++++++++++++++
 include/soc/qcom/cmd-db.h |  45 +++++++
 5 files changed, 366 insertions(+)
 create mode 100644 drivers/soc/qcom/cmd-db.c
 create mode 100644 include/soc/qcom/cmd-db.h

index c00d81dfac0b..26fb43847f4b 100644
@@ -494,6 +494,7 @@ EXPORT_SYMBOL_GPL(of_platform_default_populate);
 #ifndef CONFIG_PPC
 static const struct of_device_id reserved_mem_matches[] = {
 	{ .compatible = "qcom,rmtfs-mem" },
+	{ .compatible = "qcom,cmd-db" },
 	{ .compatible = "ramoops" },
 	{}
 };

index e050eb83341d..b12868a2b92d 100644
@@ -3,6 +3,15 @@
 #
 menu "Qualcomm SoC drivers"
 
+config QCOM_COMMAND_DB
+	bool "Qualcomm Command DB"
+	depends on (ARCH_QCOM && OF) || COMPILE_TEST
+	help
+	  Command DB queries shared memory by key string for shared system
+	  resources. Platform drivers that require to set state of a shared
+	  resource on a RPM-hardened platform must use this database to get
+	  SoC specific identifier and information for the shared resources.
+
 config QCOM_GLINK_SSR
 	tristate "Qualcomm Glink SSR driver"
 	depends on RPMSG

index dcebf2814e6d..bbd1230fc441 100644
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0
+obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o
 obj-$(CONFIG_QCOM_GLINK_SSR) +=	glink_ssr.o
 obj-$(CONFIG_QCOM_GSBI)	+=	qcom_gsbi.o
 obj-$(CONFIG_QCOM_MDT_LOADER)	+= mdt_loader.o

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

From: Mahesh Sivasubramanian <[email protected]>

Command DB provides information on shared resources like clocks, regulators etc., probed at boot by the remote subsytem and made available in shared memory.

---

Changes in v8:
- Fix node name
- Add no-map property
Changes in v7:
- Fix description of 'reg' property

Changes in v6:
- Move to bindings/reserved-memory
- Remove indirection address and use only the actual reserved memory

Changes in v4:
- Fix unwanted capitalization
- Add reg property

---
 .../bindings/reserved-memory/qcom,cmd-db.txt       | 37 ++++++++++++++++++++++
 1 file changed, 37 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reserved-memory/qcom,cmd-db.txt

new file mode 100644
index 000000000000..68395530c0a5
@@ -0,0 +1,37 @@
+Command DB
+---------
+
+Command DB is a database that provides a mapping between resource key and the
+resource address for a system resource managed by a remote processor. The data
+is stored in a shared memory region and is loaded by the remote processor.
+
+Some of the Qualcomm Technologies Inc SoC's have hardware accelerators for
+controlling shared resources. Depending on the board configuration the shared
+resource properties may change. These properties are dynamically probed by the
+remote processor and made available in the shared memory.
+
+The bindings for Command DB is specified in the reserved-memory section in
+devicetree. The devicetree representation of the command DB driver should be:
+
+Properties:
+- compatible:
+	Usage: required
+	Value type: <string>
+	Definition: Should be "qcom,cmd-db"
+
+- reg:
+	Usage: required
+	Value type: <prop encoded array>
+	Definition: The register address that points to the actual location of
+		    the Command DB in memory.
+
+Example:
+
+	reserved-memory {
+		[...]
+		reserved-memory@85fe0000 {
+			reg = <0x0 0x85fe0000 0x0 0x20000>;
+			compatible = "qcom,cmd-db";
+			no-map;
+		};
+	};

The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

Hi Andy, David,

These patches have been reviewed by our peers and have recieved no further comments in the past few weeks. Would you consider merging this in your trees?

Thanks,
Lina

Lina

When I look at:

https://git.kernel.org/pub/scm/linux/kernel/git/agross/linux.git/log/?h=for-next

I see both of your patches (plus Stephen Boyd's patch about making things endian-agnostic). ...so I think we're good. :-)

-Doug

Excellent. Thank you.

-- Lina