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Message-ID: <6069b1edf7796f3eff0d68c398eefff2@walle.cc>
Date: Tue, 14 Jan 2020 16:55:56 +0100
From: Michael Walle <michael@...le.cc>
To: linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Michael Turquette <mturquette@...libre.com>,
Stephen Boyd <sboyd@...nel.org>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v3 3/3] clk: fsl-sai: new driver
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@...le.cc>
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@...le.cc>
> + */
> +
> +#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@...le.cc>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:fsl-sai-clk");
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