[PATCH v4 4/4] clk: bcm: Add BCM63268 timer clock and reset driver

[Álvaro Fernández Rojas]

Add driver for BCM63268 timer clock and reset controller.

Signed-off-by: Álvaro Fernández Rojas <noltari@xxxxxxxxx>
---
 v4: add changes suggested by Stephen Boyd:
  - Usage of of_device_get_match_data() isn't needed.
  - Use devm_clk_hw_register_gate().
  - Drop clk_hw_unregister_gate().
 v3: add missing <linux/io.h> include to fix build warning
 v2: add changes suggested by Stephen Boyd

 drivers/clk/bcm/Kconfig              |   9 ++
 drivers/clk/bcm/Makefile             |   1 +
 drivers/clk/bcm/clk-bcm63268-timer.c | 215 +++++++++++++++++++++++++++
 3 files changed, 225 insertions(+)
 create mode 100644 drivers/clk/bcm/clk-bcm63268-timer.c

diff --git a/drivers/clk/bcm/Kconfig b/drivers/clk/bcm/Kconfig
index 77266afb1c79..a972d763eb77 100644
--- a/drivers/clk/bcm/Kconfig
+++ b/drivers/clk/bcm/Kconfig
@@ -37,6 +37,15 @@ config CLK_BCM_63XX_GATE
 	  Enable common clock framework support for Broadcom BCM63xx DSL SoCs
 	  based on the MIPS architecture
 
+config CLK_BCM63268_TIMER
+	bool "Broadcom BCM63268 timer clock and reset support"
+	depends on BMIPS_GENERIC || COMPILE_TEST
+	default BMIPS_GENERIC
+	select RESET_CONTROLLER
+	help
+	  Enable timer clock and reset support for Broadcom BCM63268 DSL SoCs
+	  based on the MIPS architecture.
+
 config CLK_BCM_KONA
 	bool "Broadcom Kona CCU clock support"
 	depends on ARCH_BCM_MOBILE || COMPILE_TEST
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index edb66b44cb27..d0b6f4b1fb08 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_CLK_BCM_63XX)	+= clk-bcm63xx.o
 obj-$(CONFIG_CLK_BCM_63XX_GATE)	+= clk-bcm63xx-gate.o
+obj-$(CONFIG_CLK_BCM63268_TIMER) += clk-bcm63268-timer.o
 obj-$(CONFIG_CLK_BCM_KONA)	+= clk-kona.o
 obj-$(CONFIG_CLK_BCM_KONA)	+= clk-kona-setup.o
 obj-$(CONFIG_CLK_BCM_KONA)	+= clk-bcm281xx.o
diff --git a/drivers/clk/bcm/clk-bcm63268-timer.c b/drivers/clk/bcm/clk-bcm63268-timer.c
new file mode 100644
index 000000000000..3631a343f0a4
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm63268-timer.c
@@ -0,0 +1,215 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * BCM63268 Timer Clock and Reset Controller Driver
+ *
+ * Copyright (C) 2023 Álvaro Fernández Rojas <noltari@xxxxxxxxx>
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/clock/bcm63268-clock.h>
+
+#define BCM63268_TIMER_RESET_SLEEP_MIN_US	10000
+#define BCM63268_TIMER_RESET_SLEEP_MAX_US	20000
+
+struct bcm63268_tclkrst_hw {
+	void __iomem *regs;
+	spinlock_t lock;
+
+	struct reset_controller_dev rcdev;
+	struct clk_hw_onecell_data data;
+};
+
+struct bcm63268_tclk_table_entry {
+	const char * const name;
+	u8 bit;
+};
+
+static const struct bcm63268_tclk_table_entry bcm63268_timer_clocks[] = {
+	{
+		.name = "ephy1",
+		.bit = BCM63268_TCLK_EPHY1,
+	}, {
+		.name = "ephy2",
+		.bit = BCM63268_TCLK_EPHY2,
+	}, {
+		.name = "ephy3",
+		.bit = BCM63268_TCLK_EPHY3,
+	}, {
+		.name = "gphy1",
+		.bit = BCM63268_TCLK_GPHY1,
+	}, {
+		.name = "dsl",
+		.bit = BCM63268_TCLK_DSL,
+	}, {
+		.name = "wakeon_ephy",
+		.bit = BCM63268_TCLK_WAKEON_EPHY,
+	}, {
+		.name = "wakeon_dsl",
+		.bit = BCM63268_TCLK_WAKEON_DSL,
+	}, {
+		.name = "fap1_pll",
+		.bit = BCM63268_TCLK_FAP1,
+	}, {
+		.name = "fap2_pll",
+		.bit = BCM63268_TCLK_FAP2,
+	}, {
+		.name = "uto_50",
+		.bit = BCM63268_TCLK_UTO_50,
+	}, {
+		.name = "uto_extin",
+		.bit = BCM63268_TCLK_UTO_EXTIN,
+	}, {
+		.name = "usb_ref",
+		.bit = BCM63268_TCLK_USB_REF,
+	}, {
+		/* sentinel */
+	}
+};
+
+static inline struct bcm63268_tclkrst_hw *
+to_bcm63268_timer_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct bcm63268_tclkrst_hw, rcdev);
+}
+
+static int bcm63268_timer_reset_update(struct reset_controller_dev *rcdev,
+				unsigned long id, bool assert)
+{
+	struct bcm63268_tclkrst_hw *reset = to_bcm63268_timer_reset(rcdev);
+	unsigned long flags;
+	uint32_t val;
+
+	spin_lock_irqsave(&reset->lock, flags);
+	val = __raw_readl(reset->regs);
+	if (assert)
+		val &= ~BIT(id);
+	else
+		val |= BIT(id);
+	__raw_writel(val, reset->regs);
+	spin_unlock_irqrestore(&reset->lock, flags);
+
+	return 0;
+}
+
+static int bcm63268_timer_reset_assert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	return bcm63268_timer_reset_update(rcdev, id, true);
+}
+
+static int bcm63268_timer_reset_deassert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	return bcm63268_timer_reset_update(rcdev, id, false);
+}
+
+static int bcm63268_timer_reset_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	bcm63268_timer_reset_update(rcdev, id, true);
+	usleep_range(BCM63268_TIMER_RESET_SLEEP_MIN_US,
+		     BCM63268_TIMER_RESET_SLEEP_MAX_US);
+
+	bcm63268_timer_reset_update(rcdev, id, false);
+	/*
+	 * Ensure component is taken out reset state by sleeping also after
+	 * deasserting the reset. Otherwise, the component may not be ready
+	 * for operation.
+	 */
+	usleep_range(BCM63268_TIMER_RESET_SLEEP_MIN_US,
+		     BCM63268_TIMER_RESET_SLEEP_MAX_US);
+
+	return 0;
+}
+
+static int bcm63268_timer_reset_status(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct bcm63268_tclkrst_hw *reset = to_bcm63268_timer_reset(rcdev);
+
+	return !(__raw_readl(reset->regs) & BIT(id));
+}
+
+static struct reset_control_ops bcm63268_timer_reset_ops = {
+	.assert = bcm63268_timer_reset_assert,
+	.deassert = bcm63268_timer_reset_deassert,
+	.reset = bcm63268_timer_reset_reset,
+	.status = bcm63268_timer_reset_status,
+};
+
+static int bcm63268_tclk_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct bcm63268_tclk_table_entry *entry;
+	struct bcm63268_tclkrst_hw *hw;
+	struct clk_hw *clk;
+	u8 maxbit = 0;
+	int i, ret;
+
+	for (entry = bcm63268_timer_clocks; entry->name; entry++)
+		maxbit = max(maxbit, entry->bit);
+	maxbit++;
+
+	hw = devm_kzalloc(&pdev->dev, struct_size(hw, data.hws, maxbit),
+			  GFP_KERNEL);
+	if (!hw)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, hw);
+
+	spin_lock_init(&hw->lock);
+
+	hw->data.num = maxbit;
+	for (i = 0; i < maxbit; i++)
+		hw->data.hws[i] = ERR_PTR(-ENODEV);
+
+	hw->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(hw->regs))
+		return PTR_ERR(hw->regs);
+
+	for (entry = bcm63268_timer_clocks; entry->name; entry++) {
+		clk = devm_clk_hw_register_gate(dev, entry->name, NULL, 0,
+						hw->regs, entry->bit,
+						CLK_GATE_BIG_ENDIAN,
+						&hw->lock);
+		if (IS_ERR(clk))
+			return PTR_ERR(clk);
+
+		hw->data.hws[entry->bit] = clk;
+	}
+
+	ret = devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
+					  &hw->data);
+	if (ret)
+		return ret;
+
+	hw->rcdev.of_node = dev->of_node;
+	hw->rcdev.ops = &bcm63268_timer_reset_ops;
+
+	ret = devm_reset_controller_register(dev, &hw->rcdev);
+	if (ret)
+		dev_err(dev, "Failed to register reset controller\n");
+
+	return 0;
+}
+
+static const struct of_device_id bcm63268_tclk_dt_ids[] = {
+	{ .compatible = "brcm,bcm63268-timer-clocks" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver bcm63268_tclk = {
+	.probe = bcm63268_tclk_probe,
+	.driver = {
+		.name = "bcm63268-timer-clock",
+		.of_match_table = bcm63268_tclk_dt_ids,
+	},
+};
+builtin_platform_driver(bcm63268_tclk);
-- 
2.30.2