diff options
Diffstat (limited to 'drivers/cpufreq/sun50i-cpufreq-nvmem.c')
| -rw-r--r-- | drivers/cpufreq/sun50i-cpufreq-nvmem.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/drivers/cpufreq/sun50i-cpufreq-nvmem.c b/drivers/cpufreq/sun50i-cpufreq-nvmem.c new file mode 100644 index 0000000000..32a9c88f8f --- /dev/null +++ b/drivers/cpufreq/sun50i-cpufreq-nvmem.c @@ -0,0 +1,217 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Allwinner CPUFreq nvmem based driver + * + * The sun50i-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/cpu.h> +#include <linux/module.h> +#include <linux/nvmem-consumer.h> +#include <linux/of.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, *sun50i_cpufreq_pdev; + +/** + * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value + * @versions: Set to the value parsed from efuse + * + * Returns 0 if success. + */ +static int sun50i_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)) + return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem), + "Could not get nvmem cell\n"); + + 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; + + /* + * We treat unexpected efuse values as if the SoC was from + * the slowest bin. Expected efuse values are 1-3, slowest + * to fastest. + */ + if (efuse_value >= 1 && efuse_value <= 3) + *versions = efuse_value - 1; + else + *versions = 0; + + kfree(speedbin); + return 0; +}; + +static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev) +{ + int *opp_tokens; + char name[MAX_NAME_LEN]; + unsigned int cpu; + u32 speed = 0; + int ret; + + opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens), + GFP_KERNEL); + if (!opp_tokens) + return -ENOMEM; + + ret = sun50i_cpufreq_get_efuse(&speed); + if (ret) { + kfree(opp_tokens); + 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) { + ret = -ENODEV; + goto free_opp; + } + + opp_tokens[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name); + if (opp_tokens[cpu] < 0) { + ret = opp_tokens[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_tokens); + return 0; + } + + ret = PTR_ERR(cpufreq_dt_pdev); + pr_err("Failed to register platform device\n"); + +free_opp: + for_each_possible_cpu(cpu) + dev_pm_opp_put_prop_name(opp_tokens[cpu]); + kfree(opp_tokens); + + return ret; +} + +static void sun50i_cpufreq_nvmem_remove(struct platform_device *pdev) +{ + int *opp_tokens = 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_tokens[cpu]); + + kfree(opp_tokens); +} + +static struct platform_driver sun50i_cpufreq_driver = { + .probe = sun50i_cpufreq_nvmem_probe, + .remove_new = sun50i_cpufreq_nvmem_remove, + .driver = { + .name = "sun50i-cpufreq-nvmem", + }, +}; + +static const struct of_device_id sun50i_cpufreq_match_list[] = { + { .compatible = "allwinner,sun50i-h6" }, + {} +}; +MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list); + +static const struct of_device_id *sun50i_cpufreq_match_node(void) +{ + const struct of_device_id *match; + struct device_node *np; + + np = of_find_node_by_path("/"); + match = of_match_node(sun50i_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 sun50i_cpufreq_init(void) +{ + const struct of_device_id *match; + int ret; + + match = sun50i_cpufreq_match_node(); + if (!match) + return -ENODEV; + + ret = platform_driver_register(&sun50i_cpufreq_driver); + if (unlikely(ret < 0)) + return ret; + + sun50i_cpufreq_pdev = + platform_device_register_simple("sun50i-cpufreq-nvmem", + -1, NULL, 0); + ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev); + if (ret == 0) + return 0; + + platform_driver_unregister(&sun50i_cpufreq_driver); + return ret; +} +module_init(sun50i_cpufreq_init); + +static void __exit sun50i_cpufreq_exit(void) +{ + platform_device_unregister(sun50i_cpufreq_pdev); + platform_driver_unregister(&sun50i_cpufreq_driver); +} +module_exit(sun50i_cpufreq_exit); + +MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver"); +MODULE_LICENSE("GPL v2"); |