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Date: Thu, 7 May 2015 11:17:05 +0100
From: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To: Sudeep Holla <sudeep.holla@....com>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Liviu Dudau <Liviu.Dudau@....com>,
"Jon Medhurst (Tixy)" <tixy@...aro.org>,
Mike Turquette <mturquette@...aro.org>,
Stephen Boyd <sboyd@...eaurora.org>,
"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>
Subject: Re: [PATCH 2/4] clk: add support for clocks provided by SCP(System
Control Processor)
On Mon, Apr 27, 2015 at 12:40:44PM +0100, Sudeep Holla wrote:
> On some ARM based systems, a separate Cortex-M based System Control
> Processor(SCP) provides the overall power, clock, reset and system
> control. System Control and Power Interface(SCPI) Message Protocol
> is defined for the communication between the Application Cores(AP)
> and the SCP.
>
> This patch adds support for the clocks provided by SCP using SCPI
> protocol.
>
> Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> Cc: Mike Turquette <mturquette@...aro.org>
> Cc: Stephen Boyd <sboyd@...eaurora.org>
> Cc: Liviu Dudau <Liviu.Dudau@....com>
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Jon Medhurst (Tixy) <tixy@...aro.org>
> Cc: linux-clk@...r.kernel.org
> ---
> drivers/clk/Kconfig | 10 ++
> drivers/clk/Makefile | 1 +
> drivers/clk/clk-scpi.c | 344 +++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 355 insertions(+)
> create mode 100644 drivers/clk/clk-scpi.c
>
> diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
> index 9897f353bf1a..906bf7dd72a2 100644
> --- a/drivers/clk/Kconfig
> +++ b/drivers/clk/Kconfig
> @@ -59,6 +59,16 @@ config COMMON_CLK_RK808
> clocked at 32KHz each. Clkout1 is always on, Clkout2 can off
> by control register.
>
> +config COMMON_CLK_SCPI
> + tristate "Clock driver controlled via SCPI interface"
> + depends on ARM_SCPI_PROTOCOL
> + ---help---
> + This driver provides support for clocks that are controlled
> + by firmware that implements the SCPI interface.
> +
> + This driver uses SCPI Message Protocol to interact with the
> + firware providing all the clock controls.
/s/firware/firmware
> +
> config COMMON_CLK_SI5351
> tristate "Clock driver for SiLabs 5351A/B/C"
> depends on I2C
> diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
> index 3d00c25382c5..442ab6ebd5b1 100644
> --- a/drivers/clk/Makefile
> +++ b/drivers/clk/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_COMMON_CLK_PALMAS) += clk-palmas.o
> obj-$(CONFIG_CLK_QORIQ) += clk-qoriq.o
> obj-$(CONFIG_COMMON_CLK_RK808) += clk-rk808.o
> obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o
> +obj-$(CONFIG_COMMON_CLK_SCPI) += clk-scpi.o
> obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o
> obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o
> obj-$(CONFIG_CLK_TWL6040) += clk-twl6040.o
> diff --git a/drivers/clk/clk-scpi.c b/drivers/clk/clk-scpi.c
> new file mode 100644
> index 000000000000..70a2d57da32d
> --- /dev/null
> +++ b/drivers/clk/clk-scpi.c
> @@ -0,0 +1,344 @@
> +/*
> + * System Control and Power Interface (SCPI) Protocol based clock driver
> + *
> + * Copyright (C) 2015 ARM Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/clkdev.h>
> +#include <linux/clk-provider.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/of.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/scpi_protocol.h>
> +
> +struct scpi_clk {
> + u32 id;
> + const char *name;
> + struct clk_hw hw;
> + struct scpi_dvfs_info *info;
> + unsigned long rate_min;
> + unsigned long rate_max;
> +};
> +
> +#define to_scpi_clk(clk) container_of(clk, struct scpi_clk, hw)
> +
> +static struct scpi_ops *scpi_ops;
> +
> +static unsigned long scpi_clk_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> +
> + return scpi_ops->clk_get_val(clk->id);
> +}
> +
> +static long scpi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> +
> + if (WARN_ON(clk->rate_min && rate < clk->rate_min))
> + rate = clk->rate_min;
> + if (WARN_ON(clk->rate_max && rate > clk->rate_max))
> + rate = clk->rate_max;
> +
> + return rate;
> +}
> +
> +static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> +
> + return scpi_ops->clk_set_val(clk->id, rate);
> +}
> +
> +static struct clk_ops scpi_clk_ops = {
> + .recalc_rate = scpi_clk_recalc_rate,
> + .round_rate = scpi_clk_round_rate,
> + .set_rate = scpi_clk_set_rate,
> +};
> +
> +/* find closest match to given frequency in OPP table */
> +static int __scpi_dvfs_round_rate(struct scpi_clk *clk, unsigned long rate)
> +{
> + int idx;
> + u32 fmin = 0, fmax = ~0, ftmp;
> + struct scpi_opp *opp = clk->info->opps;
> +
> + for (idx = 0; idx < clk->info->count; idx++, opp++) {
> + ftmp = opp->freq;
> + if (ftmp >= (u32)rate) {
> + if (ftmp <= fmax)
> + fmax = ftmp;
> + } else {
> + if (ftmp >= fmin)
> + fmin = ftmp;
> + }
> + }
Is the opp list sorted ? Can't you break instead of going through
the whole opp set ?
> + if (fmax != ~0)
> + return fmax;
> + return fmin;
return fmax != ~0 ? fmax : fmin;
> +}
> +
> +static unsigned long scpi_dvfs_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> + int idx = scpi_ops->dvfs_get_idx(clk->id);
> + struct scpi_opp *opp;
> +
> + if (idx < 0)
> + return 0;
> +
> + opp = clk->info->opps + idx;
> + return opp->freq;
> +}
> +
> +static long scpi_dvfs_round_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long *parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> +
> + return __scpi_dvfs_round_rate(clk, rate);
> +}
> +
> +static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate)
> +{
> + int idx, max_opp = clk->info->count;
> + struct scpi_opp *opp = clk->info->opps;
> +
> + for (idx = 0; idx < max_opp; idx++, opp++)
> + if (opp->freq == rate)
> + break;
return idx;
> + return (idx == max_opp) ? -EINVAL : idx;
return -EINVAL;
> +}
> +
> +static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct scpi_clk *clk = to_scpi_clk(hw);
> + int ret = __scpi_find_dvfs_index(clk, rate);
> +
> + if (ret < 0)
> + return ret;
> + return scpi_ops->dvfs_set_idx(clk->id, (u8)ret);
> +}
> +
> +static struct clk_ops scpi_dvfs_ops = {
> + .recalc_rate = scpi_dvfs_recalc_rate,
> + .round_rate = scpi_dvfs_round_rate,
> + .set_rate = scpi_dvfs_set_rate,
> +};
> +
> +static struct clk *
> +scpi_dvfs_ops_init(struct device *dev, struct device_node *np,
> + struct scpi_clk *sclk)
> +{
> + struct clk_init_data init;
> + struct scpi_dvfs_info *info;
> +
> + init.name = sclk->name;
> + init.flags = CLK_IS_ROOT;
> + init.num_parents = 0;
> + init.ops = &scpi_dvfs_ops;
> + sclk->hw.init = &init;
> +
> + info = scpi_ops->dvfs_get_info(sclk->id);
> + if (IS_ERR(info))
> + return (struct clk *)info;
Can't you just return NULL ?
> +
> + sclk->info = info;
> +
> + return devm_clk_register(dev, &sclk->hw);
> +}
> +
> +static struct clk *
> +scpi_clk_ops_init(struct device *dev, struct device_node *np,
> + struct scpi_clk *sclk)
> +{
> + struct clk_init_data init;
> + int ret;
> +
> + init.name = sclk->name;
> + init.flags = CLK_IS_ROOT;
> + init.num_parents = 0;
> + init.ops = &scpi_clk_ops;
> + sclk->hw.init = &init;
> +
> + ret = scpi_ops->clk_get_range(sclk->id, &sclk->rate_min,
> + &sclk->rate_max);
> + if (!sclk->rate_max)
> + ret = -EINVAL;
> + if (ret)
> + return ERR_PTR(ret);
Ditto, this ERR_PTR song and dance is not nice at all.
> +
> + return devm_clk_register(dev, &sclk->hw);
> +}
These two functions are identical apart from the ops, can't we have
just one function and differentiate behavior according to the matching
compatible string ?
> +static const struct of_device_id scpi_clk_match[] = {
> + { .compatible = "arm,scpi-dvfs", .data = scpi_dvfs_ops_init, },
> + { .compatible = "arm,scpi-clk", .data = scpi_clk_ops_init, },
> + {}
> +};
> +
> +static int scpi_clk_probe(struct platform_device *pdev)
> +{
> + struct clk **clks;
> + int idx, count;
> + struct clk_onecell_data *clk_data;
> + struct device *dev = &pdev->dev;
> + struct device_node *np = dev->of_node;
> + struct clk *(*clk_ops_init)(struct device *, struct device_node *,
> + struct scpi_clk *);
> +
> + if (!of_device_is_available(np))
> + return -ENODEV;
> +
> + clk_ops_init = of_match_node(scpi_clk_match, np)->data;
> + if (!clk_ops_init)
> + return -ENODEV;
> +
> + count = of_property_count_strings(np, "clock-output-names");
> + if (count < 0) {
> + dev_err(dev, "%s: invalid clock output count\n", np->name);
> + return -EINVAL;
> + }
> +
> + clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL);
> + if (!clk_data) {
> + dev_err(dev, "failed to allocate clock provider data\n");
> + return -ENOMEM;
> + }
> +
> + clks = devm_kmalloc(dev, count * sizeof(*clks), GFP_KERNEL);
> + if (!clks) {
> + dev_err(dev, "failed to allocate clock providers\n");
> + return -ENOMEM;
> + }
> +
> + for (idx = 0; idx < count; idx++) {
> + struct scpi_clk *sclk;
> + u32 val;
> +
> + sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
> + if (!sclk) {
> + dev_err(dev, "failed to allocate scpi clocks\n");
> + return -ENOMEM;
> + }
> +
> + if (of_property_read_string_index(np, "clock-output-names",
> + idx, &sclk->name)) {
> + dev_err(dev, "invalid clock name @ %s\n", np->name);
> + return -EINVAL;
> + }
> +
> + if (of_property_read_u32_index(np, "clock-indices",
> + idx, &val)) {
> + dev_err(dev, "invalid clock index @ %s\n", np->name);
> + return -EINVAL;
> + }
> +
> + sclk->id = val;
> +
> + clks[idx] = clk_ops_init(dev, np, sclk);
> + if (IS_ERR(clks[idx])) {
See above.
> + dev_err(dev, "failed to register clock '%s'\n",
> + sclk->name);
> + }
> +
> + dev_dbg(dev, "Registered clock '%s'\n", sclk->name);
> + }
> +
> + clk_data->clks = clks;
> + clk_data->clk_num = idx;
> + of_clk_add_provider(np, of_clk_src_onecell_get, clk_data);
> +
> + platform_set_drvdata(pdev, clk_data);
Where is this used ?
> +
> + return 0;
> +}
> +
> +static int scpi_clk_remove(struct platform_device *pdev)
> +{
> + of_clk_del_provider(pdev->dev.of_node);
> + platform_set_drvdata(pdev, NULL);
> + return 0;
> +}
> +
> +static struct platform_driver scpi_clk_driver = {
> + .driver = {
> + .name = "scpi_clk",
> + .of_match_table = scpi_clk_match,
> + },
> + .probe = scpi_clk_probe,
> + .remove = scpi_clk_remove,
> +};
> +
> +static int scpi_clocks_probe(struct platform_device *pdev)
> +{
> + scpi_ops = get_scpi_ops();
> + if (!scpi_ops)
> + return -ENXIO;
> +
> + return of_platform_populate(pdev->dev.of_node, scpi_clk_match,
> + NULL, &pdev->dev);
Do you really need to create a platform_device per sub-node ?
> +}
> +
> +static int scpi_clocks_remove(struct platform_device *pdev)
> +{
> + of_platform_depopulate(&pdev->dev);
> + scpi_ops = NULL;
> + return 0;
> +}
> +
> +static const struct of_device_id scpi_clocks_ids[] = {
> + { .compatible = "arm,scpi-clocks", },
> + {}
> +};
> +
> +static struct platform_driver scpi_clocks_driver = {
> + .driver = {
> + .name = "scpi_clocks",
> + .of_match_table = scpi_clocks_ids,
> + },
> + .probe = scpi_clocks_probe,
> + .remove = scpi_clocks_remove,
> +};
Why do you need two drivers for the clocks ? Isn't the parent device
tree node and respective platform device enough to initialize all
the subnodes clocks ?
> +static int __init scpi_clocks_init(void)
> +{
> + int ret;
> +
> + ret = platform_driver_register(&scpi_clk_driver);
> + if (ret)
> + return ret;
> +
> + return platform_driver_register(&scpi_clocks_driver);
See above.
Thanks,
Lorenzo
> +}
> +module_init(scpi_clocks_init);
> +
> +static void __exit scpi_clocks_exit(void)
> +{
> + platform_driver_unregister(&scpi_clk_driver);
> + platform_driver_unregister(&scpi_clocks_driver);
> +}
> +module_exit(scpi_clocks_exit);
> +
> +MODULE_AUTHOR("Sudeep Holla <sudeep.holla@....com>");
> +MODULE_DESCRIPTION("ARM SCPI clock driver");
> +MODULE_LICENSE("GPL");
> --
> 1.9.1
>
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