diff options
Diffstat (limited to 'drivers/cpufreq/bmips-cpufreq.c')
| -rw-r--r-- | drivers/cpufreq/bmips-cpufreq.c | 188 |
1 files changed, 188 insertions, 0 deletions
diff --git a/drivers/cpufreq/bmips-cpufreq.c b/drivers/cpufreq/bmips-cpufreq.c new file mode 100644 index 000000000000..1653151b77df --- /dev/null +++ b/drivers/cpufreq/bmips-cpufreq.c @@ -0,0 +1,188 @@ +/* + * CPU frequency scaling for Broadcom BMIPS SoCs + * + * Copyright (c) 2017 Broadcom + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License as + * published by the Free Software Foundation version 2. + * + * This program is distributed "as is" WITHOUT ANY WARRANTY of any + * kind, whether express or implied; without even the implied warranty + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <linux/cpufreq.h> +#include <linux/module.h> +#include <linux/of_address.h> +#include <linux/slab.h> + +/* for mips_hpt_frequency */ +#include <asm/time.h> + +#define BMIPS_CPUFREQ_PREFIX "bmips" +#define BMIPS_CPUFREQ_NAME BMIPS_CPUFREQ_PREFIX "-cpufreq" + +#define TRANSITION_LATENCY (25 * 1000) /* 25 us */ + +#define BMIPS5_CLK_DIV_SET_SHIFT 0x7 +#define BMIPS5_CLK_DIV_SHIFT 0x4 +#define BMIPS5_CLK_DIV_MASK 0xf + +enum bmips_type { + BMIPS5000, + BMIPS5200, +}; + +struct cpufreq_compat { + const char *compatible; + unsigned int bmips_type; + unsigned int clk_mult; + unsigned int max_freqs; +}; + +#define BMIPS(c, t, m, f) { \ + .compatible = c, \ + .bmips_type = (t), \ + .clk_mult = (m), \ + .max_freqs = (f), \ +} + +static struct cpufreq_compat bmips_cpufreq_compat[] = { + BMIPS("brcm,bmips5000", BMIPS5000, 8, 4), + BMIPS("brcm,bmips5200", BMIPS5200, 8, 4), + { } +}; + +static struct cpufreq_compat *priv; + +static int htp_freq_to_cpu_freq(unsigned int clk_mult) +{ + return mips_hpt_frequency * clk_mult / 1000; +} + +static struct cpufreq_frequency_table * +bmips_cpufreq_get_freq_table(const struct cpufreq_policy *policy) +{ + struct cpufreq_frequency_table *table; + unsigned long cpu_freq; + int i; + + cpu_freq = htp_freq_to_cpu_freq(priv->clk_mult); + + table = kmalloc((priv->max_freqs + 1) * sizeof(*table), GFP_KERNEL); + if (!table) + return ERR_PTR(-ENOMEM); + + for (i = 0; i < priv->max_freqs; i++) { + table[i].frequency = cpu_freq / (1 << i); + table[i].driver_data = i; + } + table[i].frequency = CPUFREQ_TABLE_END; + + return table; +} + +static unsigned int bmips_cpufreq_get(unsigned int cpu) +{ + unsigned int div; + uint32_t mode; + + switch (priv->bmips_type) { + case BMIPS5200: + case BMIPS5000: + mode = read_c0_brcm_mode(); + div = ((mode >> BMIPS5_CLK_DIV_SHIFT) & BMIPS5_CLK_DIV_MASK); + break; + default: + div = 0; + } + + return htp_freq_to_cpu_freq(priv->clk_mult) / (1 << div); +} + +static int bmips_cpufreq_target_index(struct cpufreq_policy *policy, + unsigned int index) +{ + unsigned int div = policy->freq_table[index].driver_data; + + switch (priv->bmips_type) { + case BMIPS5200: + case BMIPS5000: + change_c0_brcm_mode(BMIPS5_CLK_DIV_MASK << BMIPS5_CLK_DIV_SHIFT, + (1 << BMIPS5_CLK_DIV_SET_SHIFT) | + (div << BMIPS5_CLK_DIV_SHIFT)); + break; + default: + return -ENOTSUPP; + } + + return 0; +} + +static int bmips_cpufreq_exit(struct cpufreq_policy *policy) +{ + kfree(policy->freq_table); + + return 0; +} + +static int bmips_cpufreq_init(struct cpufreq_policy *policy) +{ + struct cpufreq_frequency_table *freq_table; + int ret; + + freq_table = bmips_cpufreq_get_freq_table(policy); + if (IS_ERR(freq_table)) { + ret = PTR_ERR(freq_table); + pr_err("%s: couldn't determine frequency table (%d).\n", + BMIPS_CPUFREQ_NAME, ret); + return ret; + } + + ret = cpufreq_generic_init(policy, freq_table, TRANSITION_LATENCY); + if (ret) + bmips_cpufreq_exit(policy); + else + pr_info("%s: registered\n", BMIPS_CPUFREQ_NAME); + + return ret; +} + +static struct cpufreq_driver bmips_cpufreq_driver = { + .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, + .verify = cpufreq_generic_frequency_table_verify, + .target_index = bmips_cpufreq_target_index, + .get = bmips_cpufreq_get, + .init = bmips_cpufreq_init, + .exit = bmips_cpufreq_exit, + .attr = cpufreq_generic_attr, + .name = BMIPS_CPUFREQ_PREFIX, +}; + +static int __init bmips_cpufreq_probe(void) +{ + struct cpufreq_compat *cc; + struct device_node *np; + + for (cc = bmips_cpufreq_compat; cc->compatible; cc++) { + np = of_find_compatible_node(NULL, "cpu", cc->compatible); + if (np) { + of_node_put(np); + priv = cc; + break; + } + } + + /* We hit the guard element of the array. No compatible CPU found. */ + if (!cc->compatible) + return -ENODEV; + + return cpufreq_register_driver(&bmips_cpufreq_driver); +} +device_initcall(bmips_cpufreq_probe); + +MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>"); +MODULE_DESCRIPTION("CPUfreq driver for Broadcom BMIPS SoCs"); +MODULE_LICENSE("GPL"); |