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authorJan Kotas <jank@cadence.com>2018-12-13 15:49:29 +0300
committerStephen Boyd <sboyd@kernel.org>2019-01-09 22:41:19 +0300
commit50cc4caf531abb2075c6973451fccdaba9f02715 (patch)
treea7b2868a62a7d3166bbd607ed4d8cdc3b80cb73e /drivers/clk/clk-fixed-mmio.c
parent5b42aac8904bfe8fcd65179c0fe71a6a1109ee53 (diff)
downloadlinux-50cc4caf531abb2075c6973451fccdaba9f02715.tar.xz
clk: Add Fixed MMIO clock driver
This patch adds a driver for Fixed MMIO clock. The driver reads a clock frequency value from a single 32-bit memory mapped register and registers it as a fixed rate clock. It can be enabled with COMMON_CLK_FIXED_MMIO Kconfig option. Signed-off-by: Jan Kotas <jank@cadence.com> [sboyd@kernel.org: Make of_fixed_mmio_clk_setup() static, use clk_hw based APIs] Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Diffstat (limited to 'drivers/clk/clk-fixed-mmio.c')
-rw-r--r--drivers/clk/clk-fixed-mmio.c101
1 files changed, 101 insertions, 0 deletions
diff --git a/drivers/clk/clk-fixed-mmio.c b/drivers/clk/clk-fixed-mmio.c
new file mode 100644
index 000000000000..d1a97d971183
--- /dev/null
+++ b/drivers/clk/clk-fixed-mmio.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Memory Mapped IO Fixed clock driver
+ *
+ * Copyright (C) 2018 Cadence Design Systems, Inc.
+ *
+ * Authors:
+ * Jan Kotas <jank@cadence.com>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/of_address.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+static struct clk_hw *fixed_mmio_clk_setup(struct device_node *node)
+{
+ struct clk_hw *clk;
+ const char *clk_name = node->name;
+ void __iomem *base;
+ u32 freq;
+ int ret;
+
+ base = of_iomap(node, 0);
+ if (!base) {
+ pr_err("%pOFn: failed to map address\n", node);
+ return ERR_PTR(-EIO);
+ }
+
+ freq = readl(base);
+ iounmap(base);
+ of_property_read_string(node, "clock-output-names", &clk_name);
+
+ clk = clk_hw_register_fixed_rate(NULL, clk_name, NULL, 0, freq);
+ if (IS_ERR(clk)) {
+ pr_err("%pOFn: failed to register fixed rate clock\n", node);
+ return clk;
+ }
+
+ ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, clk);
+ if (ret) {
+ pr_err("%pOFn: failed to add clock provider\n", node);
+ clk_hw_unregister(clk);
+ clk = ERR_PTR(ret);
+ }
+
+ return clk;
+}
+
+static void __init of_fixed_mmio_clk_setup(struct device_node *node)
+{
+ fixed_mmio_clk_setup(node);
+}
+CLK_OF_DECLARE(fixed_mmio_clk, "fixed-mmio-clock", of_fixed_mmio_clk_setup);
+
+/**
+ * This is not executed when of_fixed_mmio_clk_setup succeeded.
+ */
+static int of_fixed_mmio_clk_probe(struct platform_device *pdev)
+{
+ struct clk_hw *clk;
+
+ clk = fixed_mmio_clk_setup(pdev->dev.of_node);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ platform_set_drvdata(pdev, clk);
+
+ return 0;
+}
+
+static int of_fixed_mmio_clk_remove(struct platform_device *pdev)
+{
+ struct clk_hw *clk = platform_get_drvdata(pdev);
+
+ of_clk_del_provider(pdev->dev.of_node);
+ clk_hw_unregister_fixed_rate(clk);
+
+ return 0;
+}
+
+static const struct of_device_id of_fixed_mmio_clk_ids[] = {
+ { .compatible = "fixed-mmio-clock" },
+ { }
+};
+MODULE_DEVICE_TABLE(of, of_fixed_mmio_clk_ids);
+
+static struct platform_driver of_fixed_mmio_clk_driver = {
+ .driver = {
+ .name = "of_fixed_mmio_clk",
+ .of_match_table = of_fixed_mmio_clk_ids,
+ },
+ .probe = of_fixed_mmio_clk_probe,
+ .remove = of_fixed_mmio_clk_remove,
+};
+module_platform_driver(of_fixed_mmio_clk_driver);
+
+MODULE_AUTHOR("Jan Kotas <jank@cadence.com>");
+MODULE_DESCRIPTION("Memory Mapped IO Fixed clock driver");
+MODULE_LICENSE("GPL v2");