clk: samsung: Add Exynos5 sub-CMU clock driver

Exynos5250/5420/5800 have only one clock controller, but some of their
clock depends on respective power domains. Handling integration of clock
controller and power domain can be done using runtime PM feature of CCF
framework. This however needs a separate struct device for each power
domain. This patch adds such separate driver for a group of such clocks,
which can be instantiated more than once, each time for a different
power domain.
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>

drivers/clk/samsung/clk-exynos5-subcmu.c

+// SPDX-License-Identifier: GPL-2.0
+//
+// Copyright (c) 2018 Samsung Electronics Co., Ltd.
+// Author: Marek Szyprowski <m.szyprowski@samsung.com>
+// Common Clock Framework support for Exynos5 power-domain dependent clocks
+
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+
+#include "clk.h"
+#include "clk-exynos5-subcmu.h"
+
+static struct samsung_clk_provider *ctx;
+static const struct exynos5_subcmu_info *cmu;
+static int nr_cmus;
+
+static void exynos5_subcmu_clk_save(void __iomem *base,
+				    struct exynos5_subcmu_reg_dump *rd,
+				    unsigned int num_regs)
+{
+	for (; num_regs > 0; --num_regs, ++rd) {
+		rd->save = readl(base + rd->offset);
+		writel((rd->save & ~rd->mask) | rd->value, base + rd->offset);
+		rd->save &= rd->mask;
+	}
+};
+
+static void exynos5_subcmu_clk_restore(void __iomem *base,
+				       struct exynos5_subcmu_reg_dump *rd,
+				       unsigned int num_regs)
+{
+	for (; num_regs > 0; --num_regs, ++rd)
+		writel((readl(base + rd->offset) & ~rd->mask) | rd->save,
+		       base + rd->offset);
+}
+
+static void exynos5_subcmu_defer_gate(struct samsung_clk_provider *ctx,
+			      const struct samsung_gate_clock *list, int nr_clk)
+{
+	while (nr_clk--)
+		samsung_clk_add_lookup(ctx, ERR_PTR(-EPROBE_DEFER), list++->id);
+}
+
+/*
+ * Pass the needed clock provider context and register sub-CMU clocks
+ *
+ * NOTE: This function has to be called from the main, OF_CLK_DECLARE-
+ * initialized clock provider driver. This happens very early during boot
+ * process. Then this driver, during core_initcall registers two platform
+ * drivers: one which binds to the same device-tree node as OF_CLK_DECLARE
+ * driver and second, for handling its per-domain child-devices. Those
+ * platform drivers are bound to their devices a bit later in arch_initcall,
+ * when OF-core populates all device-tree nodes.
+ */
+void exynos5_subcmus_init(struct samsung_clk_provider *_ctx, int _nr_cmus,
+			  const struct exynos5_subcmu_info *_cmu)
+{
+	ctx = _ctx;
+	cmu = _cmu;
+	nr_cmus = _nr_cmus;
+
+	for (; _nr_cmus--; _cmu++) {
+		exynos5_subcmu_defer_gate(ctx, _cmu->gate_clks,
+					  _cmu->nr_gate_clks);
+		exynos5_subcmu_clk_save(ctx->reg_base, _cmu->suspend_regs,
+					_cmu->nr_suspend_regs);
+	}
+}
+
+static int __maybe_unused exynos5_subcmu_suspend(struct device *dev)
+{
+	struct exynos5_subcmu_info *info = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->lock, flags);
+	exynos5_subcmu_clk_save(ctx->reg_base, info->suspend_regs,
+				info->nr_suspend_regs);
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	return 0;
+}
+
+static int __maybe_unused exynos5_subcmu_resume(struct device *dev)
+{
+	struct exynos5_subcmu_info *info = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->lock, flags);
+	exynos5_subcmu_clk_restore(ctx->reg_base, info->suspend_regs,
+				   info->nr_suspend_regs);
+	spin_unlock_irqrestore(&ctx->lock, flags);
+
+	return 0;
+}
+
+static int __init exynos5_subcmu_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct exynos5_subcmu_info *info = dev_get_drvdata(dev);
+
+	pm_runtime_set_suspended(dev);
+	pm_runtime_enable(dev);
+	pm_runtime_get(dev);
+
+	ctx->dev = dev;
+	samsung_clk_register_div(ctx, info->div_clks, info->nr_div_clks);
+	samsung_clk_register_gate(ctx, info->gate_clks, info->nr_gate_clks);
+	ctx->dev = NULL;
+
+	pm_runtime_put_sync(dev);
+
+	return 0;
+}
+
+static const struct dev_pm_ops exynos5_subcmu_pm_ops = {
+	SET_RUNTIME_PM_OPS(exynos5_subcmu_suspend,
+			   exynos5_subcmu_resume, NULL)
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				     pm_runtime_force_resume)
+};
+
+static struct platform_driver exynos5_subcmu_driver __refdata = {
+	.driver	= {
+		.name = "exynos5-subcmu",
+		.suppress_bind_attrs = true,
+		.pm = &exynos5_subcmu_pm_ops,
+	},
+	.probe = exynos5_subcmu_probe,
+};
+
+static int __init exynos5_clk_register_subcmu(struct device *parent,
+					 const struct exynos5_subcmu_info *info,
+					      struct device_node *pd_node)
+{
+	struct of_phandle_args genpdspec = { .np = pd_node };
+	struct platform_device *pdev;
+
+	pdev = platform_device_alloc(info->pd_name, -1);
+	pdev->dev.parent = parent;
+	pdev->driver_override = "exynos5-subcmu";
+	platform_set_drvdata(pdev, (void *)info);
+	of_genpd_add_device(&genpdspec, &pdev->dev);
+	platform_device_add(pdev);
+
+	return 0;
+}
+
+static int __init exynos5_clk_probe(struct platform_device *pdev)
+{
+	struct device_node *np;
+	const char *name;
+	int i;
+
+	for_each_compatible_node(np, NULL, "samsung,exynos4210-pd") {
+		if (of_property_read_string(np, "label", &name) < 0)
+			continue;
+		for (i = 0; i < nr_cmus; i++)
+			if (strcmp(cmu[i].pd_name, name) == 0)
+				exynos5_clk_register_subcmu(&pdev->dev,
+							    &cmu[i], np);
+	}
+	return 0;
+}
+
+static const struct of_device_id exynos5_clk_of_match[] = {
+	{ },
+};
+
+static struct platform_driver exynos5_clk_driver __refdata = {
+	.driver	= {
+		.name = "exynos5-clock",
+		.of_match_table = exynos5_clk_of_match,
+		.suppress_bind_attrs = true,
+	},
+	.probe = exynos5_clk_probe,
+};
+
+static int __init exynos5_clk_drv_init(void)
+{
+	platform_driver_register(&exynos5_clk_driver);
+	platform_driver_register(&exynos5_subcmu_driver);
+	return 0;
+}
+core_initcall(exynos5_clk_drv_init);

drivers/clk/samsung/clk-exynos5-subcmu.h

+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef __CLK_EXYNOS5_SUBCMU_H
+#define __CLK_EXYNOS5_SUBCMU_H
+
+struct exynos5_subcmu_reg_dump {
+	u32 offset;
+	u32 value;
+	u32 mask;
+	u32 save;
+};
+
+struct exynos5_subcmu_info {
+	const struct samsung_div_clock *div_clks;
+	unsigned int nr_div_clks;
+	const struct samsung_gate_clock *gate_clks;
+	unsigned int nr_gate_clks;
+	struct exynos5_subcmu_reg_dump *suspend_regs;
+	unsigned int nr_suspend_regs;
+	const char *pd_name;
+};
+
+void exynos5_subcmus_init(struct samsung_clk_provider *ctx, int nr_cmus,
+			  const struct exynos5_subcmu_info *cmu);
+
+#endif