Re: [PATCH v5 2/4] clk: boston: Add a driver for MIPS Boston board clocks

[James Hogan <james.hogan@imgtec.com>]

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On Sat, Jun 17, 2017 at 01:52:47PM -0700, Paul Burton wrote:
> Add a driver for the clocks provided by the MIPS Boston board from
> Imagination Technologies. 2 clocks are provided - the system clock & the
> CPU clock - and each is a simple fixed rate clock whose frequency can be
> determined by reading a register provided by the board.
> 
> Signed-off-by: Paul Burton <paul.burton@imgtec.com>
> Cc: Michael Turquette <mturquette@baylibre.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> Cc: Stephen Boyd <sboyd@codeaurora.org>
> Cc: linux-clk@vger.kernel.org
> Cc: linux-mips@linux-mips.org

FWIW
Reviewed-by: James Hogan <james.hogan@imgtec.com>

Cheers
James

> 
> ---
> 
> Changes in v5:
> - Use struct clk_hw rather than struct clk.
> - Comment on reasoning for use of CLK_OF_DECLARE.
> - Drop depends on OF from Kconfig.
> - Define pr_fmt to get clearer error messages.
> 
> Changes in v4:
> - Adjust to expect the parent node to be the syscon.
> - Update MAINTAINERS entry.
> 
> Changes in v3: None
> 
> Changes in v2:
> - Support BOSTON_CLK_INPUT.
> - Register clocks with clk_register_fixed_rate during boot, removing need for clk_ops.
> - s/uint32_t/u32/.
> - Move driver to a vendor directory.
> 
>  MAINTAINERS                     |   1 +
>  drivers/clk/Kconfig             |   1 +
>  drivers/clk/Makefile            |   1 +
>  drivers/clk/imgtec/Kconfig      |   9 ++++
>  drivers/clk/imgtec/Makefile     |   1 +
>  drivers/clk/imgtec/clk-boston.c | 103 ++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 116 insertions(+)
>  create mode 100644 drivers/clk/imgtec/Kconfig
>  create mode 100644 drivers/clk/imgtec/Makefile
>  create mode 100644 drivers/clk/imgtec/clk-boston.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6a341862f5d6..2749877a4574 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8503,6 +8503,7 @@ M:	Paul Burton <paul.burton@imgtec.com>
>  L:	linux-mips@linux-mips.org
>  S:	Maintained
>  F:	Documentation/devicetree/bindings/clock/img,boston-clock.txt
> +F:	drivers/clk/imgtec/clk-boston.c
>  F:	include/dt-bindings/clock/boston-clock.h
>  
>  MIROSOUND PCM20 FM RADIO RECEIVER DRIVER
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 36cfea38135f..251a22139e73 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -219,6 +219,7 @@ config COMMON_CLK_VC5
>  
>  source "drivers/clk/bcm/Kconfig"
>  source "drivers/clk/hisilicon/Kconfig"
> +source "drivers/clk/imgtec/Kconfig"
>  source "drivers/clk/mediatek/Kconfig"
>  source "drivers/clk/meson/Kconfig"
>  source "drivers/clk/mvebu/Kconfig"
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index c19983afcb81..a4a7c5df8b93 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -59,6 +59,7 @@ obj-y					+= bcm/
>  obj-$(CONFIG_ARCH_BERLIN)		+= berlin/
>  obj-$(CONFIG_H8300)			+= h8300/
>  obj-$(CONFIG_ARCH_HISI)			+= hisilicon/
> +obj-y					+= imgtec/
>  obj-$(CONFIG_ARCH_MXC)			+= imx/
>  obj-$(CONFIG_MACH_INGENIC)		+= ingenic/
>  obj-$(CONFIG_COMMON_CLK_KEYSTONE)	+= keystone/
> diff --git a/drivers/clk/imgtec/Kconfig b/drivers/clk/imgtec/Kconfig
> new file mode 100644
> index 000000000000..f6dcb748e9c4
> --- /dev/null
> +++ b/drivers/clk/imgtec/Kconfig
> @@ -0,0 +1,9 @@
> +config COMMON_CLK_BOSTON
> +	bool "Clock driver for MIPS Boston boards"
> +	depends on MIPS || COMPILE_TEST
> +	select MFD_SYSCON
> +	---help---
> +	  Enable this to support the system & CPU clocks on the MIPS Boston
> +	  development board from Imagination Technologies. These are simple
> +	  fixed rate clocks whose rate is determined by reading a platform
> +	  provided register.
> diff --git a/drivers/clk/imgtec/Makefile b/drivers/clk/imgtec/Makefile
> new file mode 100644
> index 000000000000..ac779b8c22f2
> --- /dev/null
> +++ b/drivers/clk/imgtec/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_COMMON_CLK_BOSTON)		+= clk-boston.o
> diff --git a/drivers/clk/imgtec/clk-boston.c b/drivers/clk/imgtec/clk-boston.c
> new file mode 100644
> index 000000000000..f18f10351785
> --- /dev/null
> +++ b/drivers/clk/imgtec/clk-boston.c
> @@ -0,0 +1,103 @@
> +/*
> + * Copyright (C) 2016-2017 Imagination Technologies
> + * Author: Paul Burton <paul.burton@imgtec.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.
> + */
> +
> +#define pr_fmt(fmt) "clk-boston: " fmt
> +
> +#include <linux/clk-provider.h>
> +#include <linux/kernel.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/slab.h>
> +#include <linux/mfd/syscon.h>
> +
> +#include <dt-bindings/clock/boston-clock.h>
> +
> +#define BOSTON_PLAT_MMCMDIV		0x30
> +# define BOSTON_PLAT_MMCMDIV_CLK0DIV	(0xff << 0)
> +# define BOSTON_PLAT_MMCMDIV_INPUT	(0xff << 8)
> +# define BOSTON_PLAT_MMCMDIV_MUL	(0xff << 16)
> +# define BOSTON_PLAT_MMCMDIV_CLK1DIV	(0xff << 24)
> +
> +#define BOSTON_CLK_COUNT 3
> +
> +static u32 ext_field(u32 val, u32 mask)
> +{
> +	return (val & mask) >> (ffs(mask) - 1);
> +}
> +
> +static void __init clk_boston_setup(struct device_node *np)
> +{
> +	unsigned long in_freq, cpu_freq, sys_freq;
> +	uint mmcmdiv, mul, cpu_div, sys_div;
> +	struct clk_hw_onecell_data *onecell;
> +	struct regmap *regmap;
> +	struct clk_hw *hw;
> +	int err;
> +
> +	regmap = syscon_node_to_regmap(np->parent);
> +	if (IS_ERR(regmap)) {
> +		pr_err("failed to find regmap\n");
> +		return;
> +	}
> +
> +	err = regmap_read(regmap, BOSTON_PLAT_MMCMDIV, &mmcmdiv);
> +	if (err) {
> +		pr_err("failed to read mmcm_div register: %d\n", err);
> +		return;
> +	}
> +
> +	in_freq = ext_field(mmcmdiv, BOSTON_PLAT_MMCMDIV_INPUT) * 1000000;
> +	mul = ext_field(mmcmdiv, BOSTON_PLAT_MMCMDIV_MUL);
> +
> +	sys_div = ext_field(mmcmdiv, BOSTON_PLAT_MMCMDIV_CLK0DIV);
> +	sys_freq = mult_frac(in_freq, mul, sys_div);
> +
> +	cpu_div = ext_field(mmcmdiv, BOSTON_PLAT_MMCMDIV_CLK1DIV);
> +	cpu_freq = mult_frac(in_freq, mul, cpu_div);
> +
> +	onecell = kzalloc(sizeof(*onecell) +
> +			  (BOSTON_CLK_COUNT * sizeof(struct clk_hw *)),
> +			  GFP_KERNEL);
> +	if (!onecell)
> +		return;
> +
> +	onecell->num = BOSTON_CLK_COUNT;
> +
> +	hw = clk_hw_register_fixed_rate(NULL, "input", NULL, 0, in_freq);
> +	if (IS_ERR(hw)) {
> +		pr_err("failed to register input clock: %ld\n", PTR_ERR(hw));
> +		return;
> +	}
> +	onecell->hws[BOSTON_CLK_INPUT] = hw;
> +
> +	hw = clk_hw_register_fixed_rate(NULL, "sys", "input", 0, sys_freq);
> +	if (IS_ERR(hw)) {
> +		pr_err("failed to register sys clock: %ld\n", PTR_ERR(hw));
> +		return;
> +	}
> +	onecell->hws[BOSTON_CLK_SYS] = hw;
> +
> +	hw = clk_hw_register_fixed_rate(NULL, "cpu", "input", 0, cpu_freq);
> +	if (IS_ERR(hw)) {
> +		pr_err("failed to register cpu clock: %ld\n", PTR_ERR(hw));
> +		return;
> +	}
> +	onecell->hws[BOSTON_CLK_CPU] = hw;
> +
> +	err = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, onecell);
> +	if (err)
> +		pr_err("failed to add DT provider: %d\n", err);
> +}
> +
> +/*
> + * Use CLK_OF_DECLARE so that this driver is probed early enough to provide the
> + * CPU frequency for use with the GIC or cop0 counters/timers.
> + */
> +CLK_OF_DECLARE(clk_boston, "img,boston-clock", clk_boston_setup);
> -- 
> 2.13.1
> 
> 

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