Re: [PATCH v4 4/8] clk: qcom: Add WCSS Q6DSP clock controller for QCS404

[Bjorn Andersson <bjorn.andersson@linaro.org>]

On Sat 02 Feb 07:26 PST 2019, Govind Singh wrote:

> Add support for the WCSS QDSP clock control used on qcs404
> based devices. This would allow wcss remoteproc driver to
> control the required WCSS QDSP clock/reset controls to
> bring the subsystem out of reset and shutdown the WCSS QDSP.
> 
> Signed-off-by: Govind Singh <govinds@codeaurora.org>
> ---
>  drivers/clk/qcom/Kconfig          |   8 +
>  drivers/clk/qcom/Makefile         |   1 +
>  drivers/clk/qcom/common.c         |  20 +++
>  drivers/clk/qcom/common.h         |   3 +-
>  drivers/clk/qcom/lpasscc-sdm845.c |  23 +--
>  drivers/clk/qcom/wcsscc-qcs404.c  | 282 ++++++++++++++++++++++++++++++
>  6 files changed, 315 insertions(+), 22 deletions(-)
>  create mode 100644 drivers/clk/qcom/wcsscc-qcs404.c
> 
> diff --git a/drivers/clk/qcom/Kconfig b/drivers/clk/qcom/Kconfig
> index 23ceadc2c115..ffa240c4dd20 100644
> --- a/drivers/clk/qcom/Kconfig
> +++ b/drivers/clk/qcom/Kconfig
> @@ -222,6 +222,14 @@ config QCS_GCC_404
>  	  Say Y if you want to use multimedia devices or peripheral
>  	  devices such as UART, SPI, I2C, USB, SD/eMMC, PCIe etc.
>  
> +config QCS_WCSSCC_404
> +	tristate "QCS404 WCSS Clock Controller"

The name of this hardware block seems to be "Q6SSTOP", so I do not think
this driver should be named "wcsscc" - even if that's what its used for.

> +	select QCS_GCC_404
> +	help
> +	  Support for the WCSS clock controller on QCS404 devices.
> +	  Say Y if you want to use the WCSS branch clocks of the WCSS clock
> +	  controller to reset the WCSS subsystem.
> +
>  config SDM_GCC_845
>  	tristate "SDM845 Global Clock Controller"
>  	select QCOM_GDSC
> diff --git a/drivers/clk/qcom/Makefile b/drivers/clk/qcom/Makefile
> index 8b7871a26792..264edf5a2063 100644
> --- a/drivers/clk/qcom/Makefile
> +++ b/drivers/clk/qcom/Makefile
> @@ -38,6 +38,7 @@ obj-$(CONFIG_QCOM_CLK_RPMH) += clk-rpmh.o
>  obj-$(CONFIG_QCOM_CLK_SMD_RPM) += clk-smd-rpm.o
>  obj-$(CONFIG_SDM_DISPCC_845) += dispcc-sdm845.o
>  obj-$(CONFIG_QCS_GCC_404) += gcc-qcs404.o
> +obj-$(CONFIG_QCS_WCSSCC_404) += wcsscc-qcs404.o
>  obj-$(CONFIG_SDM_GCC_845) += gcc-sdm845.o
>  obj-$(CONFIG_SDM_LPASSCC_845) += lpasscc-sdm845.o
>  obj-$(CONFIG_SDM_VIDEOCC_845) += videocc-sdm845.o
> diff --git a/drivers/clk/qcom/common.c b/drivers/clk/qcom/common.c
> index b8064a336d46..c76ea0de3eee 100644
> --- a/drivers/clk/qcom/common.c
> +++ b/drivers/clk/qcom/common.c
> @@ -288,4 +288,24 @@ int qcom_cc_probe(struct platform_device *pdev, const struct qcom_cc_desc *desc)
>  }
>  EXPORT_SYMBOL_GPL(qcom_cc_probe);
>  
> +int qcom_cc_probe_by_index(struct platform_device *pdev, int index,
> +			   const struct qcom_cc_desc *desc)
> +{
> +	struct regmap *regmap;
> +	struct resource *res;
> +	void __iomem *base;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, index);
> +	base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(base))
> +		return -ENOMEM;
> +
> +	regmap = devm_regmap_init_mmio(&pdev->dev, base, desc->config);
> +	if (IS_ERR(regmap))
> +		return PTR_ERR(regmap);
> +
> +	return qcom_cc_really_probe(pdev, desc, regmap);
> +}
> +EXPORT_SYMBOL_GPL(qcom_cc_probe_by_index);
> +
>  MODULE_LICENSE("GPL v2");
> diff --git a/drivers/clk/qcom/common.h b/drivers/clk/qcom/common.h
> index 00196ee15e73..d9de4730b955 100644
> --- a/drivers/clk/qcom/common.h
> +++ b/drivers/clk/qcom/common.h
> @@ -68,5 +68,6 @@ extern int qcom_cc_really_probe(struct platform_device *pdev,
>  				struct regmap *regmap);
>  extern int qcom_cc_probe(struct platform_device *pdev,
>  			 const struct qcom_cc_desc *desc);
> -
> +extern int qcom_cc_probe_by_index(struct platform_device *pdev, int index,
> +				  const struct qcom_cc_desc *desc);
>  #endif
> diff --git a/drivers/clk/qcom/lpasscc-sdm845.c b/drivers/clk/qcom/lpasscc-sdm845.c

The extraction of this common code is suitable to have in its own patch.

[..]
>  static const struct of_device_id lpass_cc_sdm845_match_table[] = {
> diff --git a/drivers/clk/qcom/wcsscc-qcs404.c b/drivers/clk/qcom/wcsscc-qcs404.c
> new file mode 100644
> index 000000000000..20306b494b2d
> --- /dev/null
> +++ b/drivers/clk/qcom/wcsscc-qcs404.c
> @@ -0,0 +1,282 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>
> +#include <linux/of_address.h>
> +#include <linux/regmap.h>
> +
> +#include <dt-bindings/clock/qcom,wcss-qcs404.h>
> +
> +#include "clk-regmap.h"
> +#include "clk-branch.h"
> +#include "common.h"
> +#include "reset.h"
> +
> +/* Q6SSTOP clocks. These clocks are voted
> + * by remoteproc client when loaded from
> + * user space, system hang is seen when CCF turns
> + * off unused clocks. As a temp solution use
> + * CLK_IGNORE_UNUSED flags which prevent these
> + * clocks from being gated during bootup.
> + */
> +static struct clk_branch lcc_ahbfabric_cbc_clk = {
> +	.halt_reg = 0x1b004,
> +	.halt_check = BRANCH_VOTED,
> +	.clkr = {
> +		.enable_reg = 0x1b004,
> +		.enable_mask = BIT(0),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "lcc_ahbfabric_cbc_clk",
> +			.ops = &clk_branch2_ops,
> +			.flags = CLK_IGNORE_UNUSED,

I presume, from working on the Turing clock controller, that the reason
for marking this ignore-unused is so that clk_disable_unused() won't
try to access these registers with the necessary iface clock disabled.

I think we should try to actually represent this, rather than hack
around it. I will post the TuringCC shortly, to show what I did.

> +		},
> +	},
> +};
> +
[..]
> +
> +/* Q6SSTOP_QDSP6SS clock */
> +static struct clk_branch q6ss_xo_clk = {

The following three things are clocks, but they are part of the hardware
block that is the "remoteproc", so I don't think we should expose these
through the clock framework, but rather just write them from the
remoteproc driver directly.

> +	.halt_reg = 0x38,
> +	/* CLK_OFF would not toggle until WCSS is out of reset */
> +	.halt_check = BRANCH_HALT_SKIP,
> +	.clkr = {
> +		.enable_reg = 0x38,
> +		.enable_mask = BIT(0),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "q6ss_xo_clk",
> +			.ops = &clk_branch2_ops,
> +			.flags = CLK_IGNORE_UNUSED,
> +		},
> +	},
> +};
> +
> +static struct clk_branch q6ss_slp_clk = {
> +	.halt_reg = 0x3c,
> +	/* CLK_OFF would not toggle until WCSS is out of reset */
> +	.halt_check = BRANCH_HALT_SKIP,
> +	.clkr = {
> +		.enable_reg = 0x3c,
> +		.enable_mask = BIT(0),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "q6ss_slp_clk",
> +			.ops = &clk_branch2_ops,
> +			.flags = CLK_IGNORE_UNUSED,
> +		},
> +	},
> +};
> +
> +static struct clk_branch q6sstop_q6ss_gfmux_clk_src = {
> +	.halt_reg = 0x20,
> +	.halt_check = BRANCH_VOTED,
> +	.clkr = {
> +		.enable_reg = 0x20,
> +		.enable_mask = BIT(1) | BIT(3) | BIT(8),
> +		.hw.init = &(struct clk_init_data){
> +			.name = "q6sstop_q6ss_gfmux_clk_src",
> +			.ops = &clk_branch2_ops,
> +			.flags = CLK_IGNORE_UNUSED,
> +		},
> +	},
> +};
> +
[..]
> +static int __init wcss_cc_qcs404_init(void)
> +{
> +	return platform_driver_register(&wcss_cc_qcs404_driver);
> +}
> +subsys_initcall(wcss_cc_qcs404_init);
> +
> +static void __exit wcss_cc_qcs404_exit(void)
> +{
> +	platform_driver_unregister(&wcss_cc_qcs404_driver);
> +}
> +module_exit(wcss_cc_qcs404_exit);

The remoteproc driver won't probe early, so module_platform_driver()
should do the trick.

Regards,
Bjorn