[PATCH 2/2] drivers: misc: add ripple counter driver

Rasmus Villemoes
2021-02-26T14:16:31Z

The only purpose of this driver is to serve as a consumer of the input
clock, to prevent it from being disabled by clk_disable_unused().

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
drivers/misc/Kconfig | 7 +++++++
drivers/misc/Makefile | 1 +
drivers/misc/ripple-ctr.c | 31 +++++++++++++++++++++++++++++++
3 files changed, 39 insertions(+)
create mode 100644 drivers/misc/ripple-ctr.c

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index f532c59bb59b..44b0b6ce42df 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -445,6 +445,13 @@ config HISI_HIKEY_USB
switching between the dual-role USB-C port and the USB-A host ports
using only one USB controller.

+config RIPPLE_CTR
+ tristate "Trivial ripple counter driver"
+ help
+ This provides a stub driver for a ripple counter, whose
+ only purpose is to request and enable the clock source
+ driving the counter.
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 99b6f15a3c70..d560163068a9 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -56,3 +56,4 @@ obj-$(CONFIG_HABANA_AI) += habanalabs/
obj-$(CONFIG_UACCE) += uacce/
obj-$(CONFIG_XILINX_SDFEC) += xilinx_sdfec.o
obj-$(CONFIG_HISI_HIKEY_USB) += hisi_hikey_usb.o
+obj-$(CONFIG_RIPPLE_CTR) += ripple-ctr.o
diff --git a/drivers/misc/ripple-ctr.c b/drivers/misc/ripple-ctr.c
new file mode 100644
index 000000000000..f086eaf335df
--- /dev/null
+++ b/drivers/misc/ripple-ctr.c
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+static int ripple_ctr_probe(struct platform_device *pdev)
+{
+ struct clk *clk;
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+ return clk_prepare_enable(clk);
+}
+
+static const struct of_device_id ripple_ctr_ids[] = {
+ { .compatible = "linux,ripple-counter", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ripple_ctr_ids);
+
+static struct platform_driver ripple_ctr_driver = {
+ .driver = {
+ .name = "ripple-counter",
+ .of_match_table = ripple_ctr_ids,
+ },
+ .probe = ripple_ctr_probe,
+};
+module_platform_driver(ripple_ctr_driver);
--
2.29.2