clk: tegra: Add fixed factor peripheral clock type

Some of the peripheral clocks on Tegra are derived from one of the top-
level PLLs with a fixed factor. Support these clocks by implementing the
->enable() and ->disable() callbacks using the peripheral clock register
banks and the ->recalc_rate() by dividing the parent rate by the fixed
factor.
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/clk/tegra/Makefile

@@ -3,6 +3,7 @@ obj-y					+= clk-audio-sync.o
 obj-y					+= clk-dfll.o
 obj-y					+= clk-divider.o
 obj-y					+= clk-periph.o
+obj-y					+= clk-periph-fixed.o
 obj-y					+= clk-periph-gate.o
 obj-y					+= clk-pll.o
 obj-y					+= clk-pll-out.o

drivers/clk/tegra/clk-periph-fixed.c

+/*
+ * Copyright (c) 2015, NVIDIA CORPORATION.  All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk-provider.h>
+
+#include "clk.h"
+
+static inline struct tegra_clk_periph_fixed *
+to_tegra_clk_periph_fixed(struct clk_hw *hw)
+{
+	return container_of(hw, struct tegra_clk_periph_fixed, hw);
+}
+
+static int tegra_clk_periph_fixed_is_enabled(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	u32 mask = 1 << (fixed->num % 32), value;
+
+	value = readl(fixed->base + fixed->regs->enb_reg);
+	if (value & mask) {
+		value = readl(fixed->base + fixed->regs->rst_reg);
+		if ((value & mask) == 0)
+			return 1;
+	}
+
+	return 0;
+}
+
+static int tegra_clk_periph_fixed_enable(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	u32 mask = 1 << (fixed->num % 32);
+
+	writel(mask, fixed->base + fixed->regs->enb_set_reg);
+
+	return 0;
+}
+
+static void tegra_clk_periph_fixed_disable(struct clk_hw *hw)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	u32 mask = 1 << (fixed->num % 32);
+
+	writel(mask, fixed->base + fixed->regs->enb_clr_reg);
+}
+
+static unsigned long
+tegra_clk_periph_fixed_recalc_rate(struct clk_hw *hw,
+				   unsigned long parent_rate)
+{
+	struct tegra_clk_periph_fixed *fixed = to_tegra_clk_periph_fixed(hw);
+	unsigned long long rate;
+
+	rate = (unsigned long long)parent_rate * fixed->mul;
+	do_div(rate, fixed->div);
+
+	return (unsigned long)rate;
+}
+
+static const struct clk_ops tegra_clk_periph_fixed_ops = {
+	.is_enabled = tegra_clk_periph_fixed_is_enabled,
+	.enable = tegra_clk_periph_fixed_enable,
+	.disable = tegra_clk_periph_fixed_disable,
+	.recalc_rate = tegra_clk_periph_fixed_recalc_rate,
+};
+
+struct clk *tegra_clk_register_periph_fixed(const char *name,
+					    const char *parent,
+					    unsigned long flags,
+					    void __iomem *base,
+					    unsigned int mul,
+					    unsigned int div,
+					    unsigned int num)
+{
+	const struct tegra_clk_periph_regs *regs;
+	struct tegra_clk_periph_fixed *fixed;
+	struct clk_init_data init;
+	struct clk *clk;
+
+	regs = get_reg_bank(num);
+	if (!regs)
+		return ERR_PTR(-EINVAL);
+
+	fixed = kzalloc(sizeof(*fixed), GFP_KERNEL);
+	if (!fixed)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.flags = flags;
+	init.parent_names = parent ? &parent : NULL;
+	init.num_parents = parent ? 1 : 0;
+	init.ops = &tegra_clk_periph_fixed_ops;
+
+	fixed->base = base;
+	fixed->regs = regs;
+	fixed->mul = mul;
+	fixed->div = div;
+	fixed->num = num;
+
+	fixed->hw.init = &init;
+
+	clk = clk_register(NULL, &fixed->hw);
+	if (IS_ERR(clk))
+		kfree(fixed);
+
+	return clk;
+}

drivers/clk/tegra/clk.h

@@ -516,6 +516,23 @@ struct clk *tegra_clk_register_periph_gate(const char *name,
 		const char *parent_name, u8 gate_flags, void __iomem *clk_base,
 		unsigned long flags, int clk_num, int *enable_refcnt);
 
+struct tegra_clk_periph_fixed {
+	struct clk_hw hw;
+	void __iomem *base;
+	const struct tegra_clk_periph_regs *regs;
+	unsigned int mul;
+	unsigned int div;
+	unsigned int num;
+};
+
+struct clk *tegra_clk_register_periph_fixed(const char *name,
+					    const char *parent,
+					    unsigned long flags,
+					    void __iomem *base,
+					    unsigned int mul,
+					    unsigned int div,
+					    unsigned int num);
+
 /**
  * struct clk-periph - peripheral clock
  *