Re: [PATCH v3 3/3] clk: fsl-sai: new driver

[Michael Walle]

Am 2020-01-03 00:11, 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.
>
> Signed-off-by: Michael Walle <michael@xxxxxxxx>

Ping :)

> ---
> changes since v2:
>  - convert to platform driver, thus also use devm_ functions
>  - use new style to get the parent clock by using parent_data
>    and the new clk_hw_register_composite_pdata()
>
> changes since v1:
>  - none
>
>  drivers/clk/Kconfig       | 12 +++++
>  drivers/clk/Makefile      |  1 +
>  drivers/clk/clk-fsl-sai.c | 92 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 105 insertions(+)
>  create mode 100644 drivers/clk/clk-fsl-sai.c
>
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 45653a0e6ecd..dd1a5abc4ce8 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -174,6 +174,18 @@ 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 0696a0c1ab58..ec23fd956228 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -29,6 +29,7 @@ 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..0221180a4dd7
> --- /dev/null
> +++ b/drivers/clk/clk-fsl-sai.c
> @@ -0,0 +1,92 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Freescale SAI BCLK as a generic clock driver
> + *
> + * Copyright 2020 Michael Walle <michael@xxxxxxxx>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#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 int fsl_sai_clk_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct fsl_sai_clk *sai_clk;
> +	struct clk_parent_data pdata = { .index = 0 };
> +	void __iomem *base;
> +	struct clk_hw *hw;
> +	struct resource *res;
> +
> +	sai_clk = devm_kzalloc(dev, sizeof(*sai_clk), GFP_KERNEL);
> +	if (!sai_clk)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	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_pdata(dev, dev->of_node->name,
> +					     &pdata, 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))
> +		return PTR_ERR(hw);
> +
> +	return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
> +}
> +
> +static const struct of_device_id of_fsl_sai_clk_ids[] = {
> +	{ .compatible = "fsl,vf610-sai-clock" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, of_fsl_sai_clk_ids);
> +
> +static struct platform_driver fsl_sai_clk_driver = {
> +	.probe = fsl_sai_clk_probe,
> +	.driver		= {
> +		.name	= "fsl-sai-clk",
> +		.of_match_table = of_fsl_sai_clk_ids,
> +	},
> +};
> +module_platform_driver(fsl_sai_clk_driver);
> +
> +MODULE_DESCRIPTION("Freescale SAI bitclock-as-a-clock driver");
> +MODULE_AUTHOR("Michael Walle <michael@xxxxxxxx>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:fsl-sai-clk");