Message-Id: <20240716103025.1198495-4-claudiu.beznea.uj@bp.renesas.com>
Date: Tue, 16 Jul 2024 13:30:17 +0300
From: Claudiu <claudiu.beznea@...on.dev>
To: lee@...nel.org,
	robh@...nel.org,
	krzk+dt@...nel.org,
	conor+dt@...nel.org,
	alexandre.belloni@...tlin.com,
	geert+renesas@...der.be,
	magnus.damm@...il.com,
	mturquette@...libre.com,
	sboyd@...nel.org,
	p.zabel@...gutronix.de
Cc: devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	linux-rtc@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-clk@...r.kernel.org,
	claudiu.beznea@...on.dev,
	Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
Subject: [PATCH v2 03/11] clk: renesas: clk-vbattb: Add VBATTB clock driver

From: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>

The VBATTB IP of the Renesas RZ/G3S SoC controls the clock that is used
by the RTC. The input to the VBATTB could be a 32KHz crystal oscillator
or an external clock device. The driver detects the type of the input clock
based on the device tree clock name (xin for crystal, clkin for external
clock device).

The load capacitance of the on-board oscillator need to be configured with
renesas,vbattb-load-nanofarads DT property.

Signed-off-by: Claudiu Beznea <claudiu.beznea.uj@...renesas.com>
---

Changes in v2:
- updated patch description
- added vendor name in Kconfig flag
- used cleanup.h lock helpers
- dropped the MFD code
- updated registers offsets
- added vbattb_clk_update_bits() and used it where possible
- added vbattb_clk_need_bypass() to detect the bypass setup necessity
- changed the compatible and driver names

 drivers/clk/renesas/Kconfig      |   5 +
 drivers/clk/renesas/Makefile     |   1 +
 drivers/clk/renesas/clk-vbattb.c | 212 +++++++++++++++++++++++++++++++
 3 files changed, 218 insertions(+)
 create mode 100644 drivers/clk/renesas/clk-vbattb.c

diff --git a/drivers/clk/renesas/Kconfig b/drivers/clk/renesas/Kconfig
index 4410d16de4e2..1f5f38136eb2 100644
--- a/drivers/clk/renesas/Kconfig
+++ b/drivers/clk/renesas/Kconfig
@@ -228,6 +228,11 @@ config CLK_RZG2L
 	bool "RZ/{G2L,G2UL,G3S,V2L} family clock support" if COMPILE_TEST
 	select RESET_CONTROLLER
 
+config CLK_RENESAS_VBATTB
+	bool "Renesas VBATTB clock controller"
+	depends on MFD_RENESAS_VBATTB
+	select RESET_CONTROLLER
+
 # Generic
 config CLK_RENESAS_CPG_MSSR
 	bool "CPG/MSSR clock support" if COMPILE_TEST
diff --git a/drivers/clk/renesas/Makefile b/drivers/clk/renesas/Makefile
index f7e18679c3b8..84a2783a7b46 100644
--- a/drivers/clk/renesas/Makefile
+++ b/drivers/clk/renesas/Makefile
@@ -51,3 +51,4 @@ obj-$(CONFIG_CLK_RZG2L)			+= rzg2l-cpg.o
 obj-$(CONFIG_CLK_RENESAS_CPG_MSSR)	+= renesas-cpg-mssr.o
 obj-$(CONFIG_CLK_RENESAS_CPG_MSTP)	+= clk-mstp.o
 obj-$(CONFIG_CLK_RENESAS_DIV6)		+= clk-div6.o
+obj-$(CONFIG_CLK_RENESAS_VBATTB)	+= clk-vbattb.o
diff --git a/drivers/clk/renesas/clk-vbattb.c b/drivers/clk/renesas/clk-vbattb.c
new file mode 100644
index 000000000000..8effe141fc0b
--- /dev/null
+++ b/drivers/clk/renesas/clk-vbattb.c
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * VBATTB clock driver
+ *
+ * Copyright (C) 2024 Renesas Electronics Corp.
+ */
+
+#include <linux/cleanup.h>
+#include <linux/clk.h>
+#include <linux/clk-provider.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+
+#define VBATTB_BKSCCR			0x0
+#define VBATTB_BKSCCR_SOSEL		BIT(6)
+#define VBATTB_SOSCCR2			0x8
+#define VBATTB_SOSCCR2_SOSTP2		BIT(0)
+#define VBATTB_XOSCCR			0x14
+#define VBATTB_XOSCCR_OUTEN		BIT(16)
+#define VBATTB_XOSCCR_XSEL		GENMASK(1, 0)
+#define VBATTB_XOSCCR_XSEL_4_PF		0x0
+#define VBATTB_XOSCCR_XSEL_7_PF		0x1
+#define VBATTB_XOSCCR_XSEL_9_PF		0x2
+#define VBATTB_XOSCCR_XSEL_12_5_PF	0x3
+
+/**
+ * struct vbattb_clk - VBATTB clock data structure
+ * @base: base address
+ * @hw: clk hw
+ * @lock: lock
+ * @load_capacitance: load capacitance
+ */
+struct vbattb_clk {
+	void __iomem *base;
+	struct clk_hw hw;
+	spinlock_t lock;
+	u8 load_capacitance;
+};
+
+#define to_vbattb_clk(_hw) container_of(_hw, struct vbattb_clk, hw)
+
+static void vbattb_clk_update_bits(void __iomem *base, u32 offset, u32 mask, u32 val)
+{
+	u32 tmp;
+
+	tmp = readl_relaxed(base + offset);
+	tmp &= ~mask;
+	tmp |= (val & mask);
+	writel_relaxed(tmp, base + offset);
+}
+
+static int vbattb_clk_enable(struct clk_hw *hw)
+{
+	struct vbattb_clk *vbclk = to_vbattb_clk(hw);
+	void __iomem *base = vbclk->base;
+
+	guard(spinlock)(&vbclk->lock);
+
+	vbattb_clk_update_bits(base, VBATTB_SOSCCR2, VBATTB_SOSCCR2_SOSTP2, 0);
+	vbattb_clk_update_bits(base, VBATTB_XOSCCR, VBATTB_XOSCCR_OUTEN | VBATTB_XOSCCR_XSEL,
+			       VBATTB_XOSCCR_OUTEN | vbclk->load_capacitance);
+
+	return 0;
+}
+
+static void vbattb_clk_disable(struct clk_hw *hw)
+{
+	struct vbattb_clk *vbclk = to_vbattb_clk(hw);
+	void __iomem *base = vbclk->base;
+
+	guard(spinlock)(&vbclk->lock);
+
+	vbattb_clk_update_bits(base, VBATTB_XOSCCR, VBATTB_XOSCCR_OUTEN, 0);
+	vbattb_clk_update_bits(base, VBATTB_SOSCCR2, VBATTB_SOSCCR2_SOSTP2, VBATTB_SOSCCR2_SOSTP2);
+}
+
+static int vbattb_clk_is_enabled(struct clk_hw *hw)
+{
+	struct vbattb_clk *vbclk = to_vbattb_clk(hw);
+	void __iomem *base = vbclk->base;
+	unsigned int xosccr, sosccr2;
+
+	guard(spinlock)(&vbclk->lock);
+
+	xosccr = readl_relaxed(base + VBATTB_XOSCCR);
+	sosccr2 = readl_relaxed(base + VBATTB_SOSCCR2);
+
+	return ((xosccr & VBATTB_XOSCCR_OUTEN) && !(sosccr2 & VBATTB_SOSCCR2_SOSTP2));
+}
+
+static const struct clk_ops vbattb_clk_ops = {
+	.enable = vbattb_clk_enable,
+	.disable = vbattb_clk_disable,
+	.is_enabled = vbattb_clk_is_enabled,
+};
+
+static int vbattb_clk_validate_load_capacitance(struct vbattb_clk *vbclk, u32 load_capacitance)
+{
+	switch (load_capacitance) {
+	case 4000:
+		vbclk->load_capacitance = VBATTB_XOSCCR_XSEL_4_PF;
+		break;
+	case 7000:
+		vbclk->load_capacitance = VBATTB_XOSCCR_XSEL_7_PF;
+		break;
+	case 9000:
+		vbclk->load_capacitance = VBATTB_XOSCCR_XSEL_9_PF;
+		break;
+	case 12500:
+		vbclk->load_capacitance = VBATTB_XOSCCR_XSEL_12_5_PF;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int vbattb_clk_need_bypass(struct device *dev)
+{
+	struct clk *clkin, *xin;
+
+	clkin = devm_clk_get_optional(dev, "clkin");
+	xin = devm_clk_get_optional(dev, "xin");
+
+	if (!IS_ERR_OR_NULL(clkin) && !IS_ERR_OR_NULL(xin))
+		return -EINVAL;
+	else if (!clkin && !IS_ERR_OR_NULL(xin))
+		return 0;
+	else if (!IS_ERR_OR_NULL(clkin) && !xin)
+		return 1;
+
+	return -EINVAL;
+}
+
+static int vbattb_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct clk_parent_data parent_data = {};
+	struct device *dev = &pdev->dev;
+	struct clk_init_data init = {};
+	struct vbattb_clk *vbclk;
+	u32 load_capacitance;
+	struct clk_hw *hw;
+	int ret, bypass;
+
+	vbclk = devm_kzalloc(dev, sizeof(*vbclk), GFP_KERNEL);
+	if (!vbclk)
+		return -ENOMEM;
+
+	vbclk->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(vbclk->base))
+		return PTR_ERR(vbclk->base);
+
+	bypass = vbattb_clk_need_bypass(dev);
+	if (bypass < 0) {
+		return bypass;
+	} else if (bypass) {
+		parent_data.fw_name = "clkin";
+		bypass = VBATTB_BKSCCR_SOSEL;
+	} else {
+		parent_data.fw_name = "xin";
+	}
+
+	ret = of_property_read_u32(np, "renesas,vbattb-load-nanofarads", &load_capacitance);
+	if (ret)
+		return ret;
+
+	ret = vbattb_clk_validate_load_capacitance(vbclk, load_capacitance);
+	if (ret)
+		return ret;
+
+	vbattb_clk_update_bits(vbclk->base, VBATTB_BKSCCR, VBATTB_BKSCCR_SOSEL, bypass);
+
+	spin_lock_init(&vbclk->lock);
+
+	init.name = "vbattclk";
+	init.ops = &vbattb_clk_ops;
+	init.parent_data = &parent_data;
+	init.num_parents = 1;
+	init.flags = 0;
+
+	vbclk->hw.init = &init;
+	hw = &vbclk->hw;
+
+	ret = devm_clk_hw_register(dev, hw);
+	if (ret)
+		return ret;
+
+	return of_clk_add_hw_provider(np, of_clk_hw_simple_get, hw);
+}
+
+static const struct of_device_id vbattb_clk_match[] = {
+	{ .compatible = "renesas,r9a08g045-vbattb-clk" },
+	{ /* sentinel */ }
+};
+
+static struct platform_driver vbattb_clk_driver = {
+	.driver		= {
+		.name	= "renesas-vbattb-clk",
+		.of_match_table = vbattb_clk_match,
+	},
+	.probe = vbattb_clk_probe,
+};
+module_platform_driver(vbattb_clk_driver);
+
+MODULE_DESCRIPTION("Renesas VBATTB Clock Driver");
+MODULE_AUTHOR("Claudiu Beznea <claudiu.beznea.uj@...renesas.com>");
+MODULE_LICENSE("GPL");
-- 
2.39.2

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