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SubjectRe: [PATCH v3 1/2] cpufreq: Add sunxi nvmem based CPU scaling driver
Hi,
Changes:
1. I removed this sunxi_cpufreq_soc_data structure for now.
2. Convert to less generic name.
3. Update soc_bin xlate. (LINE:484
https://github.com/Allwinner-Homlet/H6-BSP4.9-linux/blob/master/drivers/soc/sunxi/sunxi-sid.c)

(maybe attach a file is better)

Now temporarily consider it as supporting only one platform.
Anything else to modify?

THx,
Yangtao
// SPDX-License-Identifier: GPL-2.0
/*
* Allwinner CPUFreq nvmem based driver
*
* The sun5i-cpufreq-nvmem driver reads the efuse value from the SoC to
* provide the OPP framework with required information.
*
* Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
*/

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>

#define MAX_NAME_LEN 7

#define NVMEM_MASK 0x7
#define NVMEM_SHIFT 5

static struct platform_device *cpufreq_dt_pdev, *sunxi_cpufreq_pdev;

/**
* sunxi_cpufreq_get_efuse() - Parse and return efuse value present on SoC
* @versions: Set to the value parsed from efuse
*
* Returns 0 if success.
*/
static int sunxi_cpufreq_get_efuse(u32 *versions)
{
struct nvmem_cell *speedbin_nvmem;
struct device_node *np;
struct device *cpu_dev;
u32 *speedbin, efuse_value;
size_t len;
int ret;

cpu_dev = get_cpu_device(0);
if (!cpu_dev)
return -ENODEV;

np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
if (!np)
return -ENOENT;

ret = of_device_is_compatible(np,
"allwinner,sun50i-h6-operating-points");
if (!ret) {
of_node_put(np);
return -ENOENT;
}

speedbin_nvmem = of_nvmem_cell_get(np, NULL);
of_node_put(np);
if (IS_ERR(speedbin_nvmem)) {
if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
pr_err("Could not get nvmem cell: %ld\n",
PTR_ERR(speedbin_nvmem));
return PTR_ERR(speedbin_nvmem);
}

speedbin = nvmem_cell_read(speedbin_nvmem, &len);
nvmem_cell_put(speedbin_nvmem);
if (IS_ERR(speedbin))
return PTR_ERR(speedbin);

efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
switch (efuse_value) {
case 0b0001:
*versions = 1;
break;
case 0b0011:
*versions = 2;
break;
default:
/*
* For other situations, we treat it as bin0.
* This vf table can be run for any good cpu.
*/
*versions = 0;
break;
}

kfree(speedbin);
return 0;
};

static int sunxi_cpufreq_nvmem_probe(struct platform_device *pdev)
{
struct opp_table **opp_tables;
char name[MAX_NAME_LEN];
unsigned int cpu;
u32 speed = 0;
int ret;

opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
GFP_KERNEL);
if (!opp_tables)
return -ENOMEM;

ret = sunxi_cpufreq_get_efuse(&speed);
if (ret)
return ret;

snprintf(name, MAX_NAME_LEN, "speed%d", speed);

for_each_possible_cpu(cpu) {
struct device *cpu_dev = get_cpu_device(cpu);

if (cpu_dev == NULL) {
ret = -ENODEV;
goto free_opp;
}

opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
if (IS_ERR(opp_tables[cpu])) {
ret = PTR_ERR(opp_tables[cpu]);
pr_err("Failed to set prop name\n");
goto free_opp;
}
}

cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
NULL, 0);
if (!IS_ERR(cpufreq_dt_pdev)) {
platform_set_drvdata(pdev, opp_tables);
return 0;
}

ret = PTR_ERR(cpufreq_dt_pdev);
pr_err("Failed to register platform device\n");

free_opp:
for_each_possible_cpu(cpu) {
if (IS_ERR_OR_NULL(opp_tables[cpu]))
break;
dev_pm_opp_put_prop_name(opp_tables[cpu]);
}
kfree(opp_tables);

return ret;
}

static int sunxi_cpufreq_nvmem_remove(struct platform_device *pdev)
{
struct opp_table **opp_tables = platform_get_drvdata(pdev);
unsigned int cpu;

platform_device_unregister(cpufreq_dt_pdev);

for_each_possible_cpu(cpu)
dev_pm_opp_put_prop_name(opp_tables[cpu]);

kfree(opp_tables);

return 0;
}

static struct platform_driver sunxi_cpufreq_driver = {
.probe = sunxi_cpufreq_nvmem_probe,
.remove = sunxi_cpufreq_nvmem_remove,
.driver = {
.name = "sunxi-cpufreq-nvmem",
},
};

static const struct of_device_id sunxi_cpufreq_match_list[] = {
{ .compatible = "allwinner,sun50i-h6" },
{}
};

static const struct of_device_id *sunxi_cpufreq_match_node(void)
{
const struct of_device_id *match;
struct device_node *np;

np = of_find_node_by_path("/");
match = of_match_node(sunxi_cpufreq_match_list, np);
of_node_put(np);

return match;
}

/*
* Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
* all the real activity is done in the probe, which may be defered as well.
* The init here is only registering the driver and the platform device.
*/
static int __init sunxi_cpufreq_init(void)
{
const struct of_device_id *match;
int ret;

match = sunxi_cpufreq_match_node();
if (!match)
return -ENODEV;

ret = platform_driver_register(&sunxi_cpufreq_driver);
if (unlikely(ret < 0))
return ret;

sunxi_cpufreq_pdev = platform_device_register_simple(
"sunxi-cpufreq-nvmem", -1, NULL, 0);
ret = PTR_ERR_OR_ZERO(sunxi_cpufreq_pdev);
if (ret == 0)
return 0;

platform_driver_unregister(&sunxi_cpufreq_driver);
return ret;
}
module_init(sunxi_cpufreq_init);

static void __exit sunxi_cpufreq_exit(void)
{
platform_device_unregister(sunxi_cpufreq_pdev);
platform_driver_unregister(&sunxi_cpufreq_driver);
}
module_exit(sunxi_cpufreq_exit);

MODULE_DESCRIPTION("Sunxi cpufreq driver");
MODULE_LICENSE("GPL v2");
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