Re: [PATCH] clk: sunxi: Add CSI (camera's Sensors Interface) module clock driver for sun[457]i

[Maxime Ripard <maxime.ripard@free-electrons.com>]

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Hi Yassin,

On Thu, Mar 17, 2016 at 07:43:42PM +1100, yassinjaffer@gmail.com wrote:
> From: Yassin Jaffer <yassinjaffer@gmail.com>
> 
> This patch adds a composite clock type consisting of
> a clock gate, mux, configurable dividers, and a reset control.
> 
> Signed-off-by: Yassin Jaffer <yassinjaffer@gmail.com>
> ---
>  Documentation/devicetree/bindings/clock/sunxi.txt |   1 +
>  drivers/clk/sunxi/Makefile                        |   1 +
>  drivers/clk/sunxi/clk-a10-csi.c                   | 188 ++++++++++++++++++++++
>  3 files changed, 190 insertions(+)
>  create mode 100644 drivers/clk/sunxi/clk-a10-csi.c
> 
> diff --git a/Documentation/devicetree/bindings/clock/sunxi.txt b/Documentation/devicetree/bindings/clock/sunxi.txt
> index e59f57b..c3826f7 100644
> --- a/Documentation/devicetree/bindings/clock/sunxi.txt
> +++ b/Documentation/devicetree/bindings/clock/sunxi.txt
> @@ -77,6 +77,7 @@ 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,sun4i-a10-csi-clk" - for the CSI module
>  
>  Required properties for all clocks:
>  - reg : shall be the control register address for the clock.
> diff --git a/drivers/clk/sunxi/Makefile b/drivers/clk/sunxi/Makefile
> index 3fd7901..42ce752 100644
> --- a/drivers/clk/sunxi/Makefile
> +++ b/drivers/clk/sunxi/Makefile
> @@ -7,6 +7,7 @@ obj-y += clk-a10-codec.o
>  obj-y += clk-a10-hosc.o
>  obj-y += clk-a10-mod1.o
>  obj-y += clk-a10-pll2.o
> +obj-y += clk-a10-csi.o
>  obj-y += clk-a10-ve.o
>  obj-y += clk-a20-gmac.o
>  obj-y += clk-mod0.o
> diff --git a/drivers/clk/sunxi/clk-a10-csi.c b/drivers/clk/sunxi/clk-a10-csi.c
> new file mode 100644
> index 0000000..f17d206
> --- /dev/null
> +++ b/drivers/clk/sunxi/clk-a10-csi.c
> @@ -0,0 +1,188 @@
> +/*
> + * Copyright 2016 Yassin Jaffer
> + *
> + * Yassin Jaffer <yassinjaffer@gmail.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_address.h>
> +#include <linux/reset-controller.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>
> +
> +static DEFINE_SPINLOCK(sun4i_csi_lock);
> +
> +#define SUN4I_CSI_PARENTS       5
> +#define SUN4I_CSI_GATE_BIT      31
> +#define SUN4I_CSI_RESET_BIT     30
> +#define SUN4I_CSI_MUX_SHIFT     24
> +#define SUN4I_CSI_DIV_WIDTH     5
> +#define SUN4I_CSI_DIV_SHIFT     0
> +
> +static u32 sun4i_csi_mux_table[SUN4I_CSI_PARENTS] = {
> +	0x0,
> +	0x1,
> +	0x2,
> +	0x5,
> +	0x6,
> +};
> +
> +struct csi_reset_data {
> +	void __iomem			*reg;
> +	spinlock_t			*lock; /* lock for reset handling */
> +	struct reset_controller_dev	rcdev;
> +};
> +
> +static int sun4i_csi_assert(struct reset_controller_dev *rcdev,
> +			    unsigned long id)
> +{
> +	struct csi_reset_data *data = container_of(rcdev,
> +						  struct csi_reset_data,
> +						  rcdev);
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(data->lock, flags);
> +
> +	reg = readl(data->reg);
> +	writel(reg & ~BIT(SUN4I_CSI_RESET_BIT), data->reg);
> +
> +	spin_unlock_irqrestore(data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int sun4i_csi_deassert(struct reset_controller_dev *rcdev,
> +			      unsigned long id)
> +{
> +	struct csi_reset_data *data = container_of(rcdev,
> +						  struct csi_reset_data,
> +						  rcdev);
> +	unsigned long flags;
> +	u32 reg;
> +
> +	spin_lock_irqsave(data->lock, flags);
> +
> +	reg = readl(data->reg);
> +	writel(reg | BIT(SUN4I_CSI_RESET_BIT), data->reg);
> +
> +	spin_unlock_irqrestore(data->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int sun4i_csi_of_xlate(struct reset_controller_dev *rcdev,
> +			      const struct of_phandle_args *reset_spec)
> +{
> +	if (WARN_ON(reset_spec->args_count != 0))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +static struct reset_control_ops sun4i_csi_reset_ops = {
> +	.assert		= sun4i_csi_assert,
> +	.deassert	= sun4i_csi_deassert,
> +};
> +
> +static void __init sun4i_csi_clk_setup(struct device_node *node)
> +{
> +	const char *parents[SUN4I_CSI_PARENTS];
> +	const char *clk_name = node->name;
> +	struct csi_reset_data *reset_data;
> +	struct clk_divider *div;
> +	struct clk_gate *gate;
> +	struct clk_mux *mux;
> +	void __iomem *reg;
> +	struct clk *clk;
> +	int i = 0;
> +
> +	reg = of_io_request_and_map(node, 0, of_node_full_name(node));
> +	if (IS_ERR(reg))
> +		return;
> +
> +	of_property_read_string(node, "clock-output-names", &clk_name);
> +
> +	i = of_clk_parent_fill(node, parents, SUN4I_CSI_PARENTS);
> +
> +	mux = kzalloc(sizeof(*mux), GFP_KERNEL);
> +	if (!mux)
> +		goto err_unmap;
> +
> +	mux->reg = reg;
> +	mux->shift = SUN4I_CSI_MUX_SHIFT;
> +	mux->table = sun4i_csi_mux_table;
> +	mux->lock = &sun4i_csi_lock;
> +
> +	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
> +	if (!gate)
> +		goto err_free_mux;
> +
> +	gate->reg = reg;
> +	gate->bit_idx = SUN4I_CSI_GATE_BIT;
> +	gate->lock = &sun4i_csi_lock;
> +
> +	div = kzalloc(sizeof(*div), GFP_KERNEL);
> +	if (!div)
> +		goto err_free_gate;
> +
> +	div->reg = reg;
> +	div->shift = SUN4I_CSI_DIV_SHIFT;
> +	div->width = SUN4I_CSI_DIV_WIDTH;
> +	div->lock = &sun4i_csi_lock;
> +
> +	clk = clk_register_composite(NULL, clk_name,
> +				     parents, i,
> +				     &mux->hw, &clk_mux_ops,
> +				     &div->hw, &clk_divider_ops,
> +				     &gate->hw, &clk_gate_ops,
> +				     CLK_SET_RATE_PARENT);
> +	if (IS_ERR(clk))
> +		goto err_free_div;
> +
> +	of_clk_add_provider(node, of_clk_src_simple_get, clk);
> +
> +	reset_data = kzalloc(sizeof(*reset_data), GFP_KERNEL);
> +	if (!reset_data)
> +		goto err_free_clk;
> +
> +	reset_data->reg = reg;
> +	reset_data->lock = &sun4i_csi_lock;
> +	reset_data->rcdev.nr_resets = 1;
> +	reset_data->rcdev.ops = &sun4i_csi_reset_ops;
> +	reset_data->rcdev.of_node = node;
> +	reset_data->rcdev.of_xlate = sun4i_csi_of_xlate;
> +	reset_data->rcdev.of_reset_n_cells = 0;
> +
> +	if (reset_controller_register(&reset_data->rcdev))
> +		goto err_free_reset;
> +
> +	return;
> +
> +err_free_reset:
> +	kfree(reset_data);
> +err_free_clk:
> +	clk_unregister(clk);
> +err_free_div:
> +	kfree(div);
> +err_free_gate:
> +	kfree(gate);
> +err_free_mux:
> +	kfree(mux);
> +err_unmap:
> +	iounmap(reg);
> +}
> +
> +CLK_OF_DECLARE(sun4i_csi, "allwinner,sun4i-a10-csi-clk",
> +	       sun4i_csi_clk_setup);
> +

That's great, but it shares a lot of infrastructure of boilerplate
code with the display clocks that are part of my DRM serie.

I plan to post them early next week, I'll cc you so that you can base
your clock on top of it.

Thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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