linux/drivers/cpufreq/loongson1-cpufreq.c
Viresh Kumar 5ae4a4b45d cpufreq: Remove CPUFREQ_STICKY flag
During cpufreq driver's registration, if the ->init() callback for all
the CPUs fail then there is not much point in keeping the driver around
as it will only account for more of unnecessary noise, for example
cpufreq core will try to suspend/resume the driver which never got
registered properly.

The removal of such a driver is avoided if the driver carries the
CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no
one should ever need it now. A lot of drivers do set this flag, probably
because they just copied it from other drivers.

This was added earlier for some platforms [2] because their cpufreq
drivers were getting registered before the CPUs were registered with
subsys framework. And hence they used to fail.

The same isn't true anymore though. The current code flow in the kernel
is:

start_kernel()
-> kernel_init()
   -> kernel_init_freeable()
      -> do_basic_setup()
         -> driver_init()
            -> cpu_dev_init()
               -> subsys_system_register() //For CPUs

         -> do_initcalls()
            -> cpufreq_register_driver()

Clearly, the CPUs will always get registered with subsys framework
before any cpufreq driver can get probed. Remove the flag and update the
relevant drivers.

Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/cpufreq.h?id=7cc9f0d9a1ab04cedc60d64fd8dcf7df224a3b4d # [1]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5 # [2]
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2021-02-04 19:23:20 +01:00

223 lines
5.5 KiB
C

/*
* CPU Frequency Scaling for Loongson 1 SoC
*
* Copyright (C) 2014-2016 Zhang, Keguang <keguang.zhang@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <cpufreq.h>
#include <loongson1.h>
struct ls1x_cpufreq {
struct device *dev;
struct clk *clk; /* CPU clk */
struct clk *mux_clk; /* MUX of CPU clk */
struct clk *pll_clk; /* PLL clk */
struct clk *osc_clk; /* OSC clk */
unsigned int max_freq;
unsigned int min_freq;
};
static struct ls1x_cpufreq *cpufreq;
static int ls1x_cpufreq_notifier(struct notifier_block *nb,
unsigned long val, void *data)
{
if (val == CPUFREQ_POSTCHANGE)
current_cpu_data.udelay_val = loops_per_jiffy;
return NOTIFY_OK;
}
static struct notifier_block ls1x_cpufreq_notifier_block = {
.notifier_call = ls1x_cpufreq_notifier
};
static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
unsigned int index)
{
struct device *cpu_dev = get_cpu_device(policy->cpu);
unsigned int old_freq, new_freq;
old_freq = policy->cur;
new_freq = policy->freq_table[index].frequency;
/*
* The procedure of reconfiguring CPU clk is as below.
*
* - Reparent CPU clk to OSC clk
* - Reset CPU clock (very important)
* - Reconfigure CPU DIV
* - Reparent CPU clk back to CPU DIV clk
*/
clk_set_parent(policy->clk, cpufreq->osc_clk);
__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
LS1X_CLK_PLL_DIV);
__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
LS1X_CLK_PLL_DIV);
clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
clk_set_parent(policy->clk, cpufreq->mux_clk);
dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
return 0;
}
static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
{
struct device *cpu_dev = get_cpu_device(policy->cpu);
struct cpufreq_frequency_table *freq_tbl;
unsigned int pll_freq, freq;
int steps, i;
pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
steps = 1 << DIV_CPU_WIDTH;
freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
if (!freq_tbl)
return -ENOMEM;
for (i = 0; i < (steps - 1); i++) {
freq = pll_freq / (i + 1);
if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
else
freq_tbl[i].frequency = freq;
dev_dbg(cpu_dev,
"cpufreq table: index %d: frequency %d\n", i,
freq_tbl[i].frequency);
}
freq_tbl[i].frequency = CPUFREQ_TABLE_END;
policy->clk = cpufreq->clk;
cpufreq_generic_init(policy, freq_tbl, 0);
return 0;
}
static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
{
kfree(policy->freq_table);
return 0;
}
static struct cpufreq_driver ls1x_cpufreq_driver = {
.name = "cpufreq-ls1x",
.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
.verify = cpufreq_generic_frequency_table_verify,
.target_index = ls1x_cpufreq_target,
.get = cpufreq_generic_get,
.init = ls1x_cpufreq_init,
.exit = ls1x_cpufreq_exit,
.attr = cpufreq_generic_attr,
};
static int ls1x_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
cpufreq_unregister_driver(&ls1x_cpufreq_driver);
return 0;
}
static int ls1x_cpufreq_probe(struct platform_device *pdev)
{
struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
struct clk *clk;
int ret;
if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
dev_err(&pdev->dev, "platform data missing\n");
return -EINVAL;
}
cpufreq =
devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
if (!cpufreq)
return -ENOMEM;
cpufreq->dev = &pdev->dev;
clk = devm_clk_get(&pdev->dev, pdata->clk_name);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "unable to get %s clock\n",
pdata->clk_name);
return PTR_ERR(clk);
}
cpufreq->clk = clk;
clk = clk_get_parent(clk);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "unable to get parent of %s clock\n",
__clk_get_name(cpufreq->clk));
return PTR_ERR(clk);
}
cpufreq->mux_clk = clk;
clk = clk_get_parent(clk);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "unable to get parent of %s clock\n",
__clk_get_name(cpufreq->mux_clk));
return PTR_ERR(clk);
}
cpufreq->pll_clk = clk;
clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
if (IS_ERR(clk)) {
dev_err(&pdev->dev, "unable to get %s clock\n",
pdata->osc_clk_name);
return PTR_ERR(clk);
}
cpufreq->osc_clk = clk;
cpufreq->max_freq = pdata->max_freq;
cpufreq->min_freq = pdata->min_freq;
ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
if (ret) {
dev_err(&pdev->dev,
"failed to register CPUFreq driver: %d\n", ret);
return ret;
}
ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
CPUFREQ_TRANSITION_NOTIFIER);
if (ret) {
dev_err(&pdev->dev,
"failed to register CPUFreq notifier: %d\n",ret);
cpufreq_unregister_driver(&ls1x_cpufreq_driver);
}
return ret;
}
static struct platform_driver ls1x_cpufreq_platdrv = {
.probe = ls1x_cpufreq_probe,
.remove = ls1x_cpufreq_remove,
.driver = {
.name = "ls1x-cpufreq",
},
};
module_platform_driver(ls1x_cpufreq_platdrv);
MODULE_ALIAS("platform:ls1x-cpufreq");
MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
MODULE_LICENSE("GPL");