linux-kernel - Re: [PATCH 2/2] clk: fsl-sai: new driver

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Date:   Mon, 02 Dec 2019 22:46:08 +0100
From:   Michael Walle <michael@...le.cc>
To:     linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 2/2] clk: fsl-sai: new driver

Hi,

Am 2019-11-23 00:56, schrieb Michael Walle:
> With this driver it is possible to use the BCLK pin of the SAI module 
> as
> a generic clock output. This is esp. useful if you want to drive a 
> clock
> to an audio codec. Because the output only allows integer divider 
> values
> the audio codec needs an integrated PLL.

ping :)

will someone pull this driver? Or have any remarks?

Here is the board what would use this driver:
https://lore.kernel.org/linux-devicetree/20191123201317.25861-5-michael@walle.cc/

-michael


> 
> Signed-off-by: Michael Walle <michael@...le.cc>
> ---
>  drivers/clk/Kconfig       | 12 ++++++
>  drivers/clk/Makefile      |  1 +
>  drivers/clk/clk-fsl-sai.c | 84 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 97 insertions(+)
>  create mode 100644 drivers/clk/clk-fsl-sai.c
> 
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index c44247d0b83e..d3bd43e8a912 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -167,6 +167,18 @@ config COMMON_CLK_CS2000_CP
>  	help
>  	  If you say yes here you get support for the CS2000 clock 
> multiplier.
> 
> +config COMMON_CLK_FSL_SAI
> +	bool "Clock driver for BCLK of Freescale SAI cores"
> +	depends on ARCH_LAYERSCAPE || COMPILE_TEST
> +	help
> +	  This driver supports the Freescale SAI (Synchronous Audio 
> Interface)
> +	  to be used as a generic clock output. Some SoCs have restrictions
> +	  regarding the possible pin multiplexer settings. Eg. on some SoCs
> +	  two SAI interfaces can only be enabled together. If just one is
> +	  needed, the BCLK pin of the second one can be used as general
> +	  purpose clock output. Ideally, it can be used to drive an audio
> +	  codec (sometimes known as MCLK).
> +
>  config COMMON_CLK_GEMINI
>  	bool "Clock driver for Cortina Systems Gemini SoC"
>  	depends on ARCH_GEMINI || COMPILE_TEST
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 0138fb14e6f8..139f55e544a8 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -28,6 +28,7 @@ obj-$(CONFIG_ARCH_CLPS711X)		+= clk-clps711x.o
>  obj-$(CONFIG_COMMON_CLK_CS2000_CP)	+= clk-cs2000-cp.o
>  obj-$(CONFIG_ARCH_EFM32)		+= clk-efm32gg.o
>  obj-$(CONFIG_COMMON_CLK_FIXED_MMIO)	+= clk-fixed-mmio.o
> +obj-$(CONFIG_COMMON_CLK_FSL_SAI)	+= clk-fsl-sai.o
>  obj-$(CONFIG_COMMON_CLK_GEMINI)		+= clk-gemini.o
>  obj-$(CONFIG_COMMON_CLK_ASPEED)		+= clk-aspeed.o
>  obj-$(CONFIG_MACH_ASPEED_G6)		+= clk-ast2600.o
> diff --git a/drivers/clk/clk-fsl-sai.c b/drivers/clk/clk-fsl-sai.c
> new file mode 100644
> index 000000000000..b92054d15ab1
> --- /dev/null
> +++ b/drivers/clk/clk-fsl-sai.c
> @@ -0,0 +1,84 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Freescale SAI BCLK as a generic clock driver
> + *
> + * Copyright 2019 Kontron Europe GmbH
> + */
> +
> +#include <linux/clk-provider.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/slab.h>
> +
> +#define I2S_CSR		0x00
> +#define I2S_CR2		0x08
> +#define CSR_BCE_BIT	28
> +#define CR2_BCD		BIT(24)
> +#define CR2_DIV_SHIFT	0
> +#define CR2_DIV_WIDTH	8
> +
> +struct fsl_sai_clk {
> +	struct clk_divider div;
> +	struct clk_gate gate;
> +	spinlock_t lock;
> +};
> +
> +static void __init fsl_sai_clk_setup(struct device_node *node)
> +{
> +	const char *clk_name = node->name;
> +	struct fsl_sai_clk *sai_clk;
> +	unsigned int num_parents;
> +	const char *parent_name;
> +	void __iomem *base;
> +	struct clk_hw *hw;
> +
> +	num_parents = of_clk_get_parent_count(node);
> +	if (!num_parents) {
> +		pr_err("%s: no parent found", clk_name);
> +		return;
> +	}
> +
> +	parent_name = of_clk_get_parent_name(node, 0);
> +
> +	sai_clk = kzalloc(sizeof(*sai_clk), GFP_KERNEL);
> +	if (!sai_clk)
> +		return;
> +
> +	base = of_iomap(node, 0);
> +	if (base == NULL) {
> +		pr_err("%s: failed to map register space", clk_name);
> +		goto err;
> +	}
> +
> +	spin_lock_init(&sai_clk->lock);
> +
> +	sai_clk->gate.reg = base + I2S_CSR;
> +	sai_clk->gate.bit_idx = CSR_BCE_BIT;
> +	sai_clk->gate.lock = &sai_clk->lock;
> +
> +	sai_clk->div.reg = base + I2S_CR2;
> +	sai_clk->div.shift = CR2_DIV_SHIFT;
> +	sai_clk->div.width = CR2_DIV_WIDTH;
> +	sai_clk->div.lock = &sai_clk->lock;
> +
> +	/* set clock direction, we are the BCLK master */
> +	writel(CR2_BCD, base + I2S_CR2);
> +
> +	hw = clk_hw_register_composite(NULL, clk_name, &parent_name, 1,
> +				       NULL, NULL,
> +				       &sai_clk->div.hw, &clk_divider_ops,
> +				       &sai_clk->gate.hw, &clk_gate_ops,
> +				       CLK_SET_RATE_GATE);
> +	if (IS_ERR(hw))
> +		goto err;
> +
> +	of_clk_add_hw_provider(node, of_clk_hw_simple_get, hw);
> +
> +	return;
> +
> +err:
> +	kfree(sai_clk);
> +}
> +
> +CLK_OF_DECLARE(fsl_sai_clk, "fsl,vf610-sai-clock", fsl_sai_clk_setup);