[PATCH v2 3/8] DT: clk: sunxi: add binding doc for the multi-bus-gates clock

[PATCH v2 3/8] DT: clk: sunxi: add binding doc for the multi-bus-gates clock

[Andre Przywara]

Recent Allwinner SoCs introduced a bus gates clock which can have
different parents for individual gates.
For the time being we encoded this relation in the driver.
This commit specifies a new binding which allows to encode this in
the DT by using a child node for each parent clock used. This allows
to specify any kind of relation efficiently and also keeps the very
same kernel driver for all SoCs at the same time.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
---
 Documentation/devicetree/bindings/clock/sunxi.txt | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
index c09f59b..323af8e 100644
--- a/Documentation/devicetree/bindings/clock/sunxi.txt
+++ b/Documentation/devicetree/bindings/clock/sunxi.txt
@@ -79,6 +79,7 @@ Required properties:
 	"allwinner,sun9i-a80-usb-mod-clk" - for usb gates + resets on A80
 	"allwinner,sun9i-a80-usb-phy-clk" - for usb phy gates + resets on A80
 	"allwinner,sun4i-a10-ve-clk" - for the Video Engine clock
+	"allwinner,sunxi-multi-bus-gates-clk" - for the multi-parent bus gates
 
 Required properties for all clocks:
 - reg : shall be the control register address for the clock.
@@ -119,6 +120,11 @@ For "allwinner,sun6i-a31-pll6-clk", there are 2 outputs. The first output
 is the normal PLL6 output, or "pll6". The second output is rate doubled
 PLL6, or "pll6x2".
 
+The "allwinner,sunxi-multi-bus-gates-clk" holds the actual clocks in
+child nodes, where each one specifies the parent clock that the particular
+gates are depending from. The child nodes each follow the common clock
+binding as described in this document.
+
 The "allwinner,*-mmc-clk" clocks have three different outputs: the
 main clock, with the ID 0, and the output and sample clocks, with the
 IDs 1 and 2, respectively.
-- 
2.6.4

Re: [PATCH v2 3/8] DT: clk: sunxi: add binding doc for the multi-bus-gates clock

[Rob Herring]

On Wed, Feb 17, 2016 at 11:43:55AM +0000, Andre Przywara wrote:
> Recent Allwinner SoCs introduced a bus gates clock which can have
> different parents for individual gates.
> For the time being we encoded this relation in the driver.
> This commit specifies a new binding which allows to encode this in
> the DT by using a child node for each parent clock used. This allows
> to specify any kind of relation efficiently and also keeps the very
> same kernel driver for all SoCs at the same time.
> 
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
> ---
>  Documentation/devicetree/bindings/clock/sunxi.txt | 6 ++++++
>  1 file changed, 6 insertions(+)

Whether this makes sense or not for sunxi, I don't know. But for the 
binding:

Acked-by: Rob Herring <robh@kernel.org>

[PATCH v2 4/8] clk: sunxi: add generic multi-parent bus clock gates driver

[Andre Przywara]

The Allwinner H3 SoC introduced bus clock gates with potentially
different parents per clock gate. The H3 driver chose to hardcode the
actual parent clock relation in the code.
Add a new driver (which has the potential to drive the H3 and also
the simple clock gates as well) which uses the power of DT to describe
this relationship in an elegant and flexible way.
Using one subnode for every parent clock we get away with a single
DT compatible match, which can be used as a fallback value in the
actual DTs without the need to add specific compatible strings to the
code.  This avoids adding a new driver or function for every new SoC.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Acked-by: Jean-Francois Moine <moinejf@free.fr>
---
 drivers/clk/sunxi/Makefile          |   1 +
 drivers/clk/sunxi/clk-multi-gates.c | 105 ++++++++++++++++++++++++++++++++++++
 2 files changed, 106 insertions(+)
 create mode 100644 drivers/clk/sunxi/clk-multi-gates.c

diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
index 3fd7901..3a9dc31 100644
--- a/drivers/clk/sunxi/Makefile
+++ b/drivers/clk/sunxi/Makefile
@@ -11,6 +11,7 @@ obj-y += clk-a10-ve.o
 obj-y += clk-a20-gmac.o
 obj-y += clk-mod0.o
 obj-y += clk-simple-gates.o
+obj-y += clk-multi-gates.o
 obj-y += clk-sun8i-bus-gates.o
 obj-y += clk-sun8i-mbus.o
 obj-y += clk-sun9i-core.o
diff --git a/drivers/clk/sunxi/clk-multi-gates.c b/drivers/clk/sunxi/clk-multi-gates.c
new file mode 100644
index 0000000..76e715a
--- /dev/null
+++ b/drivers/clk/sunxi/clk-multi-gates.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2016 ARM Ltd.
+ *
+ * Based on clk-sun8i-bus-gates.c, which is:
+ *  Copyright (C) 2015 Jens Kuske <jenskuske@gmail.com>
+ * Based on clk-simple-gates.c, which is:
+ *  Copyright 2015 Maxime Ripard <maxime.ripard@free-electrons.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that 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.
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+
+static DEFINE_SPINLOCK(gates_lock);
+
+static void __init sunxi_parse_parent(struct device_node *node,
+				      struct clk_onecell_data *clk_data,
+				      void __iomem *reg)
+{
+	const char *parent = of_clk_get_parent_name(node, 0);
+	const char *clk_name;
+	struct property *prop;
+	struct clk *clk;
+	const __be32 *p;
+	int index, i = 0;
+
+	of_property_for_each_u32(node, "clock-indices", prop, p, index) {
+		of_property_read_string_index(node, "clock-output-names",
+					      i, &clk_name);
+
+		clk = clk_register_gate(NULL, clk_name, parent, 0,
+					reg + 4 * (index / 32), index % 32,
+					0, &gates_lock);
+		i++;
+		if (IS_ERR(clk)) {
+			pr_warn("could not register gate clock \"%s\"\n",
+				clk_name);
+			continue;
+		}
+		if (clk_data->clks[index])
+			pr_warn("bus-gate clock %s: index #%d already registered as %s\n",
+				clk_name, index, "?");
+		else
+			clk_data->clks[index] = clk;
+	}
+}
+
+static void __init sunxi_multi_bus_gates_init(struct device_node *node)
+{
+	struct clk_onecell_data *clk_data;
+	struct device_node *child;
+	struct property *prop;
+	struct resource res;
+	void __iomem *reg;
+	const __be32 *p;
+	int number = 0;
+	int index;
+
+	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
+	if (IS_ERR(reg))
+		return;
+
+	clk_data = kmalloc(sizeof(struct clk_onecell_data), GFP_KERNEL);
+	if (!clk_data)
+		goto err_unmap;
+
+	for_each_child_of_node(node, child)
+		of_property_for_each_u32(child, "clock-indices", prop, p, index)
+			number = max(number, index);
+
+	clk_data->clks = kcalloc(number + 1, sizeof(struct clk *), GFP_KERNEL);
+	if (!clk_data->clks)
+		goto err_free_data;
+
+	for_each_child_of_node(node, child)
+		sunxi_parse_parent(child, clk_data, reg);
+
+	clk_data->clk_num = number + 1;
+	if (of_clk_add_provider(node, of_clk_src_onecell_get, clk_data))
+		pr_err("registering bus-gate clock %s failed\n", node->name);
+
+	return;
+
+err_free_data:
+	kfree(clk_data);
+err_unmap:
+	iounmap(reg);
+	of_address_to_resource(node, 0, &res);
+	release_mem_region(res.start, resource_size(&res));
+}
+
+CLK_OF_DECLARE(sunxi_multi_bus_gates, "allwinner,sunxi-multi-bus-gates-clk",
+	       sunxi_multi_bus_gates_init);
-- 
2.6.4