Re: [RESEND/PATCH v6 3/3] clk: qcom: Add A53 clock driver

[Stephen Boyd <sboyd@codeaurora.org>]

On 10/19, Georgi Djakov wrote:
> Add a driver for the A53 Clock Controller. It is a hardware block that
> implements a combined mux and half integer divider functionality. It can
> choose between a fixed-rate clock or the dedicated A53 PLL. The source
> and the divider can be set both at the same time.
> 
> This is required for enabling CPU frequency scaling on platforms like
> MSM8916.
> 

Please Cc DT reviewers.

> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> ---
>  .../devicetree/bindings/clock/qcom,a53cc.txt       |  22 +++
>  drivers/clk/qcom/Kconfig                           |   8 ++
>  drivers/clk/qcom/Makefile                          |   1 +
>  drivers/clk/qcom/a53cc.c                           | 155 +++++++++++++++++++++
>  4 files changed, 186 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/qcom,a53cc.txt
>  create mode 100644 drivers/clk/qcom/a53cc.c
> 
> diff --git a/Documentation/devicetree/bindings/clock/qcom,a53cc.txt b/Documentation/devicetree/bindings/clock/qcom,a53cc.txt
> new file mode 100644
> index 000000000000..a025f062f177
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/qcom,a53cc.txt
> @@ -0,0 +1,22 @@
> +Qualcomm A53 CPU Clock Controller Binding
> +------------------------------------------------
> +The A53 CPU Clock Controller is hardware, which provides a combined
> +mux and divider functionality for the CPU clocks. It can choose between
> +a fixed rate clock and the dedicated A53 PLL.
> +
> +Required properties :
> +- compatible : shall contain:
> +
> +			"qcom,a53cc"
> +
> +- reg : shall contain base register location and length
> +	of the APCS region
> +- #clock-cells : shall contain 1
> +
> +Example:
> +
> +	apcs: syscon@b011000 {
> +		compatible = "qcom,a53cc", "syscon";

Why is it a syscon? Is that part used?

> +		reg = <0x0b011000 0x1000>;
> +		#clock-cells = <1>;
> +	};
> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
> index a889f0b14b54..59dfcdc340e4 100644
> --- a/drivers/clk/qcom/Kconfig
> +++ b/drivers/clk/qcom/Kconfig
> @@ -159,3 +159,11 @@ config QCOM_A53PLL
>  	  support for CPU frequencies above 1GHz.
>  	  Say Y if you want to support CPU frequency scaling on devices
>  	  such as MSM8916.
> +
> +config QCOM_A53CC
> +	bool "A53 Clock Controller"

Can't these configs be tristate? Same applies to A53PLL.

> +	depends on COMMON_CLK_QCOM && QCOM_A53PLL
> +	help
> +	  Support for the A53 clock controller on some Qualcomm devices.
> +	  Say Y if you want to support CPU frequency scaling on devices
> +	  such as MSM8916.
> diff --git a/drivers/clk/qcom/a53cc.c b/drivers/clk/qcom/a53cc.c
> new file mode 100644
> index 000000000000..4d20db9da407
> --- /dev/null
> +++ b/drivers/clk/qcom/a53cc.c
> @@ -0,0 +1,155 @@
> +/*
> + * Copyright (c) 2016, Linaro Limited
> + * Copyright (c) 2014, The Linux Foundation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * 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.h>
> +#include <linux/clk-provider.h>
> +#include <linux/cpu.h>

Is this include used?

> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include "clk-regmap.h"
> +#include "clk-regmap-mux-div.h"
> +
> +enum {
> +	P_GPLL0,
> +	P_A53PLL,
> +};
> +
> +static const struct parent_map gpll0_a53cc_map[] = {
> +	{ P_GPLL0, 4 },
> +	{ P_A53PLL, 5 },
> +};
> +
> +static const char * const gpll0_a53cc[] = {
> +	"gpll0_vote",
> +	"a53pll",
> +};
> +
> +static const struct regmap_config a53cc_regmap_config = {
> +	.reg_bits		= 32,
> +	.reg_stride		= 4,
> +	.val_bits		= 32,
> +	.max_register		= 0x1000,
> +	.fast_io		= true,
> +	.val_format_endian	= REGMAP_ENDIAN_LITTLE,
> +};
> +
> +static const struct of_device_id qcom_a53cc_match_table[] = {
> +	{ .compatible = "qcom,a53cc" },
> +	{ }
> +};

Can you move this down next to the driver please?

> +
> +/*
> + * We use the notifier function for switching to a temporary safe configuration
> + * (mux and divider), while the a53 pll is reconfigured.
> + */
> +static int a53cc_notifier_cb(struct notifier_block *nb, unsigned long event,
> +			     void *data)
> +{
> +	int ret = 0;
> +	struct clk_regmap_mux_div *md = container_of(nb,
> +						     struct clk_regmap_mux_div,
> +						     clk_nb);
> +
> +	if (event == PRE_RATE_CHANGE)
> +		ret = __mux_div_set_src_div(md, md->safe_src, md->safe_div);
> +
> +	return notifier_from_errno(ret);
> +}
> +
> +static int qcom_a53cc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct clk_regmap_mux_div *a53cc;
> +	struct resource *res;
> +	void __iomem *base;
> +	struct clk *pclk;
> +	struct regmap *regmap;
> +	struct clk_init_data init;

 = { } for safety?

> +	int ret;
> +
> +	a53cc = devm_kzalloc(dev, sizeof(*a53cc), GFP_KERNEL);
> +	if (!a53cc)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	a53cc->reg_offset = 0x50,
> +	a53cc->hid_width = 5,
> +	a53cc->hid_shift = 0,
> +	a53cc->src_width = 3,
> +	a53cc->src_shift = 8,
> +	a53cc->safe_src = 4,
> +	a53cc->safe_div = 3,

Replace commas with semicolons please.

Also do we need the safe things to be part of the struct? The
notifier is here so we could just as easily hard code these
things in the notifier.

> +	a53cc->parent_map = gpll0_a53cc_map,
> +
> +	init.name = "a53mux",
> +	init.parent_names = gpll0_a53cc,
> +	init.num_parents = 2,
> +	init.ops = &clk_regmap_mux_div_ops,
> +	init.flags = CLK_SET_RATE_PARENT;
> +	a53cc->clkr.hw.init = &init;
> +
> +	pclk = __clk_lookup(gpll0_a53cc[1]);
> +	if (!pclk)
> +		return -EPROBE_DEFER;
> +
> +	a53cc->clk_nb.notifier_call = a53cc_notifier_cb;
> +	ret = clk_notifier_register(pclk, &a53cc->clk_nb);
> +	if (ret) {
> +		dev_err(dev, "failed to register clock notifier: %d\n", ret);
> +		return ret;
> +	}

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project