[PATCH v7 0/3] Adding brcmstb-hwspinlock support

[PATCH v7 0/3] Adding brcmstb-hwspinlock support

[Kamal Dasu]

This series adds hardware semaphore support for Broadcom set-top SoCs
via the generic hwspinlock framework.

The semaphore registers live in the sundry block; the DT binding
describes only the semaphore register range. The compatible is
brcm,bcm7038-sun-top-ctrl-semaphore (BCM7038 is where this block first
appeared on set-top chips).

The driver has been tested built-in and as a module.

v7 changes :
 - Rebase: Whole series rebased onto Linux 7.1-rc1 (254f49634ee1) so it
   applies cleanly on current upstream.
 - Reviewed-by tag (PATCH 1/3, dt-bindings): Krzysztof Kozlowski's

v6 changes:
Addressed review comments from Krzysztof Kozlowski:
 - Renamed DT binding YAML file from "brcm,brcmstb-hwspinlock.yaml"
   to "brcm,bcm7038-sun-top-ctrl-semaphore.yaml" to match the
   compatible string
 - Updated $id in the YAML to match the new filename
 - Updated MAINTAINERS F: entry to match the new filename

v5 changes:
Addressed review comments from Krzysztof Kozlowski:
 - Changed compatible to "brcm,bcm7038-sun-top-ctrl-semaphore"
   using the SoC where the semaphore hardware was first introduced,
   following the brcm,bcm7038-l1-intc convention

v4 changes:
Addressed review comments from Krzysztof Kozlowski and Rob Herring:
 - Renamed compatible from "brcm,brcmstb-hwspinlock" to
   "brcm,brcmstb-sun-top-ctrl-semaphore" to use the hardware name
 - Added description block to the DT binding YAML explaining what
   the semaphore registers are and their relationship to the sundry
   block
 - Fixed typo in Kconfig "Setttop" -> "Settop"
 - Fixed email typo in MODULE_AUTHOR

v3 changes:
Added detailed explanation in the all commit messages as per review
comments
 - Added description of 'sundry' ip block that the hardware semaphore
   belongs to
 - Added reasoning for using common compatible string

v2 changes:
Addressed following review comments:
 - fixed ordering of obj brcmstb_hwspinlock.o in Makefile
 - fixed ordering of 'config HWSPINLOCK_BRCMSTB' block in Kconfig
 - Renamed BRCMSTB_MAX_SEMAPHORES to BRCMSTB_NUM_SEMAPHORES
 - Removed unnecessary platform_set_drvdata(pdev, bank);

Also addressing duplicate PATCH 1/3 sent in error as part of v1 change.

v1 changes:
based on fixes made to Initial patch:
Link: https://github.com/intel-lab-lkp/linux/commits/Kamal-Dasu/dt-bindings-brcmstb-hwspinlock-support-for-hwspinlock/20250712-034624
Link: https://lore.kernel.org/r/20250711154221.928164-4-kamal.dasu%40broadcom.com
  [PATCH 2/4] hwspinlock: brcmstb hardware semaphore support

All the review comments and build warning have been fixed.

Kamal Dasu (3):
  dt-bindings: hwlock: Adding brcmstb-hwspinlock support
  hwspinlock: brcmstb hardware semaphore support
  MAINTAINERS: adding entry for BRCMSTB HWSPINLOCK driver

 .../brcm,bcm7038-sun-top-ctrl-semaphore.yaml  | 44 +++++++++
 MAINTAINERS                                   |  8 ++
 drivers/hwspinlock/Kconfig                    | 10 ++
 drivers/hwspinlock/Makefile                   |  1 +
 drivers/hwspinlock/brcmstb_hwspinlock.c       | 96 +++++++++++++++++++
 5 files changed, 159 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml
 create mode 100644 drivers/hwspinlock/brcmstb_hwspinlock.c

-- 
2.34.1

[PATCH v7 1/3] dt-bindings: hwlock: Adding brcmstb-hwspinlock support

[Kamal Dasu]

The Broadcom settop SoCs have hardware semaphores as part of the
"sundry" IP block which has other controls that do not belong anywhere
else e.g. pin/mux controls, SoC identification, drive strength, reset
controls, and other misc bits are part of this block.

Adding brcmstb-hwspinlock bindings which allows the hwspinlock driver
to iomap only the 16 hardware semaphore registers that are part of all
settop SoCs. The semaphore registers are based on the BCM7038 SoC
where they were first introduced in settop chips.

Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
 .../brcm,bcm7038-sun-top-ctrl-semaphore.yaml  | 44 +++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml

diff --git a/Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml b/Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml
new file mode 100644
index 000000000000..552f334256b5
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml
@@ -0,0 +1,44 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Broadcom Settop Sundry Block Hardware Semaphore
+
+description:
+  Broadcom settop SoCs contain 16 hardware semaphore registers
+  (SEMAPHORE_0 through SEMAPHORE_15) that provide hardware-arbitrated
+  mutual exclusion between drivers running on the SoC.
+
+  The semaphore registers belong to the sundry hardware block. The
+  node describes the semaphore register range carved out of the larger
+  sundry block address space.
+
+maintainers:
+  - Kamal Dasu <kamal.dasu@broadcom.com>
+
+properties:
+  compatible:
+    const: brcm,bcm7038-sun-top-ctrl-semaphore
+
+  "#hwlock-cells":
+    const: 1
+
+  reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - "#hwlock-cells"
+
+additionalProperties: false
+
+examples:
+  - |
+    hwlock@404038 {
+        compatible = "brcm,bcm7038-sun-top-ctrl-semaphore";
+        reg = <0x404038 0x40>;
+        #hwlock-cells = <1>;
+    };
-- 
2.34.1

[PATCH v7 2/3] hwspinlock: brcmstb hardware semaphore support

[Kamal Dasu]

Broadcom settop SoCs have common 16 hardware semaphore registers that
can be used as part of the kernel hardware spinlock framework. The
hardware semaphores are part of the 'sundry' ip block that also has
controls like pin/mux controls, SoC identification, drive strength,
reset controls, and other misc bits.

Adding support for brcmstb_hwspinlock that only maps sundry block
registers SUN_TOP_CTRL_SEMAPHORE_[0:15] to implement the hardware
spinlock operations. Change allows other Broadcom settop drivers to
call hwspin_trylock() and hwspin_unlock() interfaces to make use of
hwspinlock framework. Other driver dt nodes just need to provide a
reference to the &hwspinlock and lock id to make use of a particular
hardware lock.
e.g. hwlocks = <&hwspinlock0 0>;

Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
---
 drivers/hwspinlock/Kconfig              | 10 +++
 drivers/hwspinlock/Makefile             |  1 +
 drivers/hwspinlock/brcmstb_hwspinlock.c | 96 +++++++++++++++++++++++++
 3 files changed, 107 insertions(+)
 create mode 100644 drivers/hwspinlock/brcmstb_hwspinlock.c

diff --git a/drivers/hwspinlock/Kconfig b/drivers/hwspinlock/Kconfig
index d84e00084ee2..3a81a6785e45 100644
--- a/drivers/hwspinlock/Kconfig
+++ b/drivers/hwspinlock/Kconfig
@@ -8,6 +8,16 @@ menuconfig HWSPINLOCK
 
 if HWSPINLOCK
 
+config HWSPINLOCK_BRCMSTB
+	tristate "Broadcom Settop Hardware Semaphore functionality"
+	depends on ARCH_BRCMSTB || COMPILE_TEST
+	help
+	  Broadcom settop hwspinlock driver.
+	  Say y here to support the Broadcom Hardware Semaphore functionality, which
+	  provides a synchronisation mechanism on the SoC.
+
+	  If unsure, say N.
+
 config HWSPINLOCK_OMAP
 	tristate "OMAP Hardware Spinlock device"
 	depends on ARCH_OMAP4 || SOC_OMAP5 || SOC_DRA7XX || SOC_AM33XX || SOC_AM43XX || ARCH_K3 || COMPILE_TEST
diff --git a/drivers/hwspinlock/Makefile b/drivers/hwspinlock/Makefile
index 3a740805949d..379443987b94 100644
--- a/drivers/hwspinlock/Makefile
+++ b/drivers/hwspinlock/Makefile
@@ -4,6 +4,7 @@
 #
 
 obj-$(CONFIG_HWSPINLOCK)		+= hwspinlock_core.o
+obj-$(CONFIG_HWSPINLOCK_BRCMSTB)	+= brcmstb_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_OMAP)		+= omap_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_QCOM)		+= qcom_hwspinlock.o
 obj-$(CONFIG_HWSPINLOCK_SPRD)		+= sprd_hwspinlock.o
diff --git a/drivers/hwspinlock/brcmstb_hwspinlock.c b/drivers/hwspinlock/brcmstb_hwspinlock.c
new file mode 100644
index 000000000000..7a5a35e741f3
--- /dev/null
+++ b/drivers/hwspinlock/brcmstb_hwspinlock.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * brcmstb HWSEM driver
+ *
+ * Copyright (C) 2025 Broadcom
+ *
+ */
+
+#include <linux/delay.h>
+#include <linux/hwspinlock.h>
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include "hwspinlock_internal.h"
+
+#define BRCMSTB_NUM_SEMAPHORES		16
+#define RESET_SEMAPHORE			0
+
+#define HWSPINLOCK_VAL			'L'
+
+static int brcmstb_hwspinlock_trylock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = (void __iomem *)lock->priv;
+
+	writel(HWSPINLOCK_VAL, lock_addr);
+
+	return (readl(lock_addr) == HWSPINLOCK_VAL);
+}
+
+static void brcmstb_hwspinlock_unlock(struct hwspinlock *lock)
+{
+	void __iomem *lock_addr = (void __iomem *)lock->priv;
+
+	/* release the lock by writing 0 to it */
+	writel(RESET_SEMAPHORE, lock_addr);
+}
+
+static void brcmstb_hwspinlock_relax(struct hwspinlock *lock)
+{
+	ndelay(50);
+}
+
+static const struct hwspinlock_ops brcmstb_hwspinlock_ops = {
+	.trylock	= brcmstb_hwspinlock_trylock,
+	.unlock		= brcmstb_hwspinlock_unlock,
+	.relax		= brcmstb_hwspinlock_relax,
+};
+
+static int brcmstb_hwspinlock_probe(struct platform_device *pdev)
+{
+	struct hwspinlock_device *bank;
+	struct hwspinlock *hwlock;
+	void __iomem *io_base;
+	int i, num_locks = BRCMSTB_NUM_SEMAPHORES;
+
+	io_base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(io_base)) {
+		dev_err(&pdev->dev, "semaphore iobase mapping error\n");
+		return PTR_ERR(io_base);
+	}
+
+	bank = devm_kzalloc(&pdev->dev, struct_size(bank, lock, num_locks),
+			    GFP_KERNEL);
+	if (!bank)
+		return -ENOMEM;
+
+	for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++)
+		hwlock->priv = (void __iomem *)(io_base + sizeof(u32) * i);
+
+	return devm_hwspin_lock_register(&pdev->dev, bank,
+					 &brcmstb_hwspinlock_ops,
+					 0, num_locks);
+}
+
+static const struct of_device_id brcmstb_hwspinlock_ids[] = {
+	{ .compatible = "brcm,bcm7038-sun-top-ctrl-semaphore", },
+	{ /* end */ },
+};
+MODULE_DEVICE_TABLE(of, brcmstb_hwspinlock_ids);
+
+static struct platform_driver brcmstb_hwspinlock_driver = {
+	.probe		= brcmstb_hwspinlock_probe,
+	.driver		= {
+		.name	= "brcmstb_hwspinlock",
+		.of_match_table = brcmstb_hwspinlock_ids,
+	},
+};
+
+module_platform_driver(brcmstb_hwspinlock_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Hardware Spinlock driver for brcmstb");
+MODULE_AUTHOR("Kamal Dasu <kamal.dasu@broadcom.com>");
-- 
2.34.1

[PATCH v7 3/3] MAINTAINERS: adding entry for BRCMSTB HWSPINLOCK driver

[Kamal Dasu]

Adding myself to the maintainers list for the hwspinlock
driver on broadcom settop platforms.

Signed-off-by: Kamal Dasu <kamal.dasu@broadcom.com>
---
 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 2fb1c75afd16..4f3dfc6a090c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5244,6 +5244,14 @@ S:	Supported
 F:	Documentation/devicetree/bindings/gpio/brcm,brcmstb-gpio.yaml
 F:	drivers/gpio/gpio-brcmstb.c
 
+BROADCOM BRCMSTB HWSPINLOCK DRIVER
+M:	Kamal Dasu <kamal.dasu@broadcom.com>
+R:	Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
+L:	linux-remoteproc@vger.kernel.org
+S:	Supported
+F:	Documentation/devicetree/bindings/hwlock/brcm,bcm7038-sun-top-ctrl-semaphore.yaml
+F:	drivers/hwspinlock/brcmstb_hwspinlock.c
+
 BROADCOM BRCMSTB I2C DRIVER
 M:	Kamal Dasu <kamal.dasu@broadcom.com>
 R:	Broadcom internal kernel review list <bcm-kernel-feedback-list@broadcom.com>
-- 
2.34.1