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Date: Mon, 1 Dec 2014 23:19:52 +0000
From: James Hogan <james.hogan@...tec.com>
To: Mike Turquette <mturquette@...aro.org>,
linux-metag@...r.kernel.org, linux-kernel@...r.kernel.org,
devicetree@...r.kernel.org
Cc: Heiko Stuebner <heiko@...ech.de>,
James Hogan <james.hogan@...tec.com>
Subject: [PATCH v2 02/16] clk: tz1090: add gate bank clock driver
Add a clock driver for banks of clock gates in the TZ1090 SoC. A single
32 bit register controls up to 32 separate clock gates. The generic
clock gate clock operations are wrapped in order to acquire and release
the Meta global exclusive lock (__global_lock2) to ensure atomicity with
other non-Linux cores and threads which may need to control some of the
clocks.
The tz1090_clk_register_gate_bank() helper function can be used to
register a gate bank from static initialisation data. Macros are
provided in tz1090/clk.h to aid the creation of this data, for example:
GATE_BANK(tz1090_perip_clken, 0, PERIP_CLKEN,
/* bit in out */
GATE( 0, "@sys", "sys_scb0")
GATE( 1, "@sys", "sys_scb1")
GATE( 2, "@sys", "sys_scb2")
...
);
...
clk_register_gate_bank(p, &tz1090_perip_clken);
Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: Mike Turquette <mturquette@...aro.org>
Cc: linux-metag@...r.kernel.org
---
Changes since v1 (patch 6):
- Renamed function prefixes from clk_tz1090_ to tz1090_clk_ for
consistency with the rest.
- Drop DT binding as it will be instantiated directly from a provider.
- Add tz1090_clk_register_gate_bank() to conveniently register a bank of
gates in a clock provider from static initilisation data.
- Extend tz1090/clk.h interface for easy static initialisation with
macros.
---
drivers/clk/tz1090/Makefile | 2 +
drivers/clk/tz1090/clk-tz1090-gate-bank.c | 149 ++++++++++++++++++++++++++++++
drivers/clk/tz1090/clk.h | 49 ++++++++++
3 files changed, 200 insertions(+)
create mode 100644 drivers/clk/tz1090/clk-tz1090-gate-bank.c
diff --git a/drivers/clk/tz1090/Makefile b/drivers/clk/tz1090/Makefile
index a2ace14..ab88f53 100644
--- a/drivers/clk/tz1090/Makefile
+++ b/drivers/clk/tz1090/Makefile
@@ -1,2 +1,4 @@
# Makefile for TZ1090-specific clocks
obj-y += clk.o
+
+obj-y += clk-tz1090-gate-bank.o
diff --git a/drivers/clk/tz1090/clk-tz1090-gate-bank.c b/drivers/clk/tz1090/clk-tz1090-gate-bank.c
new file mode 100644
index 0000000..5834afd
--- /dev/null
+++ b/drivers/clk/tz1090/clk-tz1090-gate-bank.c
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2013-2014 Imagination Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License version 2 as published by the
+ * Free Software Foundation.
+ *
+ * TZ1090 Clock gate bank
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <asm/global_lock.h>
+
+#include "clk.h"
+
+/**
+ * struct tz1090_clk_gate_priv - tz1090 gating clock
+ *
+ * @mux: the parent class
+ * @ops: pointer to clk_ops of parent class
+ *
+ * Clock which can gate its output. Extends basic mux by using a global
+ * exclusive lock when read-modify-writing the mux field so that multiple
+ * threads/cores can use different fields in the same register.
+ */
+struct tz1090_clk_gate_priv {
+ struct clk_gate gate;
+ const struct clk_ops *ops;
+};
+
+static inline struct tz1090_clk_gate_priv *to_tz1090_clk_gate(struct clk_hw *hw)
+{
+ struct clk_gate *gate = container_of(hw, struct clk_gate, hw);
+
+ return container_of(gate, struct tz1090_clk_gate_priv, gate);
+}
+
+/* Acquire exclusive lock since other cores may access the same register */
+static int tz1090_clk_gate_enable(struct clk_hw *hw)
+{
+ struct tz1090_clk_gate_priv *gate = to_tz1090_clk_gate(hw);
+ int ret;
+ unsigned long flags;
+
+ __global_lock2(flags);
+ ret = gate->ops->enable(&gate->gate.hw);
+ __global_unlock2(flags);
+
+ return ret;
+}
+
+/* Acquire exclusive lock since other cores may access the same register */
+static void tz1090_clk_gate_disable(struct clk_hw *hw)
+{
+ struct tz1090_clk_gate_priv *gate = to_tz1090_clk_gate(hw);
+ unsigned long flags;
+
+ __global_lock2(flags);
+ gate->ops->disable(&gate->gate.hw);
+ __global_unlock2(flags);
+}
+
+static int tz1090_clk_gate_is_enabled(struct clk_hw *hw)
+{
+ struct tz1090_clk_gate_priv *gate = to_tz1090_clk_gate(hw);
+
+ return gate->ops->is_enabled(&gate->gate.hw);
+}
+
+static const struct clk_ops tz1090_clk_gate_ops = {
+ .enable = tz1090_clk_gate_enable,
+ .disable = tz1090_clk_gate_disable,
+ .is_enabled = tz1090_clk_gate_is_enabled,
+};
+
+/**
+ * __register_gate() - register a TZ1090 gate clock with clock framework.
+ * @name: name of this clock
+ * @parent_name: name of this clock's parent
+ * @flags: framework-specific flags for this clock
+ * @reg: register address to control gating of this clock
+ * @bit_idx: which bit in the register controls gating of this clock
+ * @clk_gate_flags: gate-specific flags for this clock
+ */
+static struct clk *__init __register_gate(const char *name,
+ const char *parent_name,
+ unsigned long flags,
+ void __iomem *reg,
+ u8 bit_idx,
+ u8 clk_gate_flags)
+{
+ struct tz1090_clk_gate_priv *gate;
+ struct clk *clk;
+ struct clk_init_data init;
+
+ /* allocate the gate */
+ gate = kzalloc(sizeof(struct tz1090_clk_gate_priv), GFP_KERNEL);
+ if (!gate)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = name;
+ init.ops = &tz1090_clk_gate_ops;
+ init.flags = flags | CLK_IS_BASIC;
+ init.parent_names = (parent_name ? &parent_name : NULL);
+ init.num_parents = (parent_name ? 1 : 0);
+
+ /* struct clk_gate assignments */
+ gate->gate.reg = reg;
+ gate->gate.bit_idx = bit_idx;
+ gate->gate.flags = clk_gate_flags;
+ gate->gate.hw.init = &init;
+
+ /* struct tz1090_clk_gate_priv assignments */
+ gate->ops = &clk_gate_ops;
+
+ clk = clk_register(NULL, &gate->gate.hw);
+
+ if (IS_ERR(clk))
+ kfree(gate);
+
+ return clk;
+}
+
+/**
+ * tz1090_clk_register_gate_bank() - Register bank of gates with a provider.
+ * @p: TZ1090 clock provider.
+ * @bank: Data describing gate bank.
+ */
+void __init tz1090_clk_register_gate_bank(struct tz1090_clk_provider *p,
+ const struct tz1090_clk_gate_bank *bank)
+{
+ const struct tz1090_clk_gate *gate;
+ struct clk *clk;
+ unsigned int id = bank->id_base;
+
+ for (gate = bank->gates; gate->name; ++gate, ++id) {
+ clk = __register_gate(tz1090_clk_xlate(p, gate->name),
+ tz1090_clk_xlate(p, gate->parent),
+ CLK_IGNORE_UNUSED | CLK_SET_RATE_PARENT,
+ p->base + bank->reg_base, gate->shift, 0);
+ p->clk_data.clks[id] = clk;
+ }
+}
diff --git a/drivers/clk/tz1090/clk.h b/drivers/clk/tz1090/clk.h
index c20e7b4..06274b7 100644
--- a/drivers/clk/tz1090/clk.h
+++ b/drivers/clk/tz1090/clk.h
@@ -34,4 +34,53 @@ const char *tz1090_clk_xlate(struct tz1090_clk_provider *p,
const char *clk_name);
void tz1090_clk_register_provider(struct tz1090_clk_provider *p);
+
+/* Clock gate banks */
+
+/**
+ * struct tz1090_clk_gate - Describes an individual gate in a bank.
+ * @shift: Shift of bit controlling gate within the bank control register.
+ * @name: Name of gated clock to provide.
+ * @parent: Name of parent/source clock.
+ */
+struct tz1090_clk_gate {
+ unsigned int shift;
+ const char *name;
+ const char *parent;
+};
+
+/**
+ * struct tz1090_clk_gate_bank - Describes a gate bank.
+ * @id_base: Base id of bank in provider.
+ * Individual gates get the id id_base + index in gates array.
+ * @reg_base: Offset of gate bank register in the MMIO region.
+ * @gates: Pointer to array of gates in the bank, terminated by one with a
+ * NULL name field.
+ */
+struct tz1090_clk_gate_bank {
+ unsigned int id_base;
+ unsigned long reg_base;
+ const struct tz1090_clk_gate *gates;
+};
+
+#define GATE(_shift, _parent, _name) \
+ { \
+ .shift = (_shift), \
+ .name = (_name), \
+ .parent = (_parent), \
+ },
+
+#define GATE_BANK(_name, _id, _reg, _gates) \
+ static const struct tz1090_clk_gate_bank _name __initconst = { \
+ .id_base = (_id), \
+ .reg_base = (_reg), \
+ .gates = (const struct tz1090_clk_gate[]) { \
+ _gates \
+ { .name = NULL } \
+ }, \
+ }
+
+void tz1090_clk_register_gate_bank(struct tz1090_clk_provider *p,
+ const struct tz1090_clk_gate_bank *bank);
+
#endif
--
2.0.4
--
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