diff options
Diffstat (limited to 'drivers/pwm/pwm-intel-lgm.c')
| -rw-r--r-- | drivers/pwm/pwm-intel-lgm.c | 244 |
1 files changed, 244 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-intel-lgm.c b/drivers/pwm/pwm-intel-lgm.c new file mode 100644 index 000000000000..e9e54dda07aa --- /dev/null +++ b/drivers/pwm/pwm-intel-lgm.c @@ -0,0 +1,244 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2020 Intel Corporation. + * + * Limitations: + * - The hardware supports fixed period & configures only 2-wire mode. + * - Supports normal polarity. Does not support changing polarity. + * - When PWM is disabled, output of PWM will become 0(inactive). It doesn't + * keep track of running period. + * - When duty cycle is changed, PWM output may be a mix of previous setting + * and new setting for the first period. From second period, the output is + * based on new setting. + * - It is a dedicated PWM fan controller. There are no other consumers for + * this PWM controller. + */ +#include <linux/bitfield.h> +#include <linux/clk.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/mod_devicetable.h> +#include <linux/pwm.h> +#include <linux/regmap.h> +#include <linux/reset.h> + +#define LGM_PWM_FAN_CON0 0x0 +#define LGM_PWM_FAN_EN_EN BIT(0) +#define LGM_PWM_FAN_EN_DIS 0x0 +#define LGM_PWM_FAN_EN_MSK BIT(0) +#define LGM_PWM_FAN_MODE_2WIRE 0x0 +#define LGM_PWM_FAN_MODE_MSK BIT(1) +#define LGM_PWM_FAN_DC_MSK GENMASK(23, 16) + +#define LGM_PWM_FAN_CON1 0x4 +#define LGM_PWM_FAN_MAX_RPM_MSK GENMASK(15, 0) + +#define LGM_PWM_MAX_RPM (BIT(16) - 1) +#define LGM_PWM_DEFAULT_RPM 4000 +#define LGM_PWM_MAX_DUTY_CYCLE (BIT(8) - 1) + +#define LGM_PWM_DC_BITS 8 + +#define LGM_PWM_PERIOD_2WIRE_NS (40 * NSEC_PER_MSEC) + +struct lgm_pwm_chip { + struct pwm_chip chip; + struct regmap *regmap; + u32 period; +}; + +static inline struct lgm_pwm_chip *to_lgm_pwm_chip(struct pwm_chip *chip) +{ + return container_of(chip, struct lgm_pwm_chip, chip); +} + +static int lgm_pwm_enable(struct pwm_chip *chip, bool enable) +{ + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip); + struct regmap *regmap = pc->regmap; + + return regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_EN_MSK, + enable ? LGM_PWM_FAN_EN_EN : LGM_PWM_FAN_EN_DIS); +} + +static int lgm_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm, + const struct pwm_state *state) +{ + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip); + u32 duty_cycle, val; + int ret; + + /* The hardware only supports normal polarity and fixed period. */ + if (state->polarity != PWM_POLARITY_NORMAL || state->period < pc->period) + return -EINVAL; + + if (!state->enabled) + return lgm_pwm_enable(chip, 0); + + duty_cycle = min_t(u64, state->duty_cycle, pc->period); + val = duty_cycle * LGM_PWM_MAX_DUTY_CYCLE / pc->period; + + ret = regmap_update_bits(pc->regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_DC_MSK, + FIELD_PREP(LGM_PWM_FAN_DC_MSK, val)); + if (ret) + return ret; + + return lgm_pwm_enable(chip, 1); +} + +static void lgm_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_state *state) +{ + struct lgm_pwm_chip *pc = to_lgm_pwm_chip(chip); + u32 duty, val; + + state->enabled = regmap_test_bits(pc->regmap, LGM_PWM_FAN_CON0, + LGM_PWM_FAN_EN_EN); + state->polarity = PWM_POLARITY_NORMAL; + state->period = pc->period; /* fixed period */ + + regmap_read(pc->regmap, LGM_PWM_FAN_CON0, &val); + duty = FIELD_GET(LGM_PWM_FAN_DC_MSK, val); + state->duty_cycle = DIV_ROUND_UP(duty * pc->period, LGM_PWM_MAX_DUTY_CYCLE); +} + +static const struct pwm_ops lgm_pwm_ops = { + .get_state = lgm_pwm_get_state, + .apply = lgm_pwm_apply, + .owner = THIS_MODULE, +}; + +static void lgm_pwm_init(struct lgm_pwm_chip *pc) +{ + struct regmap *regmap = pc->regmap; + u32 con0_val; + + con0_val = FIELD_PREP(LGM_PWM_FAN_MODE_MSK, LGM_PWM_FAN_MODE_2WIRE); + pc->period = LGM_PWM_PERIOD_2WIRE_NS; + regmap_update_bits(regmap, LGM_PWM_FAN_CON1, LGM_PWM_FAN_MAX_RPM_MSK, + LGM_PWM_DEFAULT_RPM); + regmap_update_bits(regmap, LGM_PWM_FAN_CON0, LGM_PWM_FAN_MODE_MSK, + con0_val); +} + +static const struct regmap_config lgm_pwm_regmap_config = { + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, +}; + +static void lgm_clk_release(void *data) +{ + struct clk *clk = data; + + clk_disable_unprepare(clk); +} + +static int lgm_clk_enable(struct device *dev, struct clk *clk) +{ + int ret; + + ret = clk_prepare_enable(clk); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, lgm_clk_release, clk); +} + +static void lgm_reset_control_release(void *data) +{ + struct reset_control *rst = data; + + reset_control_assert(rst); +} + +static int lgm_reset_control_deassert(struct device *dev, struct reset_control *rst) +{ + int ret; + + ret = reset_control_deassert(rst); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, lgm_reset_control_release, rst); +} + +static int lgm_pwm_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct reset_control *rst; + struct lgm_pwm_chip *pc; + void __iomem *io_base; + struct clk *clk; + int ret; + + pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL); + if (!pc) + return -ENOMEM; + + platform_set_drvdata(pdev, pc); + + io_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(io_base)) + return PTR_ERR(io_base); + + pc->regmap = devm_regmap_init_mmio(dev, io_base, &lgm_pwm_regmap_config); + if (IS_ERR(pc->regmap)) + return dev_err_probe(dev, PTR_ERR(pc->regmap), + "failed to init register map\n"); + + clk = devm_clk_get(dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n"); + + ret = lgm_clk_enable(dev, clk); + if (ret) + return dev_err_probe(dev, ret, "failed to enable clock\n"); + + rst = devm_reset_control_get_exclusive(dev, NULL); + if (IS_ERR(rst)) + return dev_err_probe(dev, PTR_ERR(rst), + "failed to get reset control\n"); + + ret = lgm_reset_control_deassert(dev, rst); + if (ret) + return dev_err_probe(dev, ret, "cannot deassert reset control\n"); + + pc->chip.dev = dev; + pc->chip.ops = &lgm_pwm_ops; + pc->chip.npwm = 1; + pc->chip.base = -1; + + lgm_pwm_init(pc); + + ret = pwmchip_add(&pc->chip); + if (ret < 0) + return dev_err_probe(dev, ret, "failed to add PWM chip\n"); + + return 0; +} + +static int lgm_pwm_remove(struct platform_device *pdev) +{ + struct lgm_pwm_chip *pc = platform_get_drvdata(pdev); + + return pwmchip_remove(&pc->chip); +} + +static const struct of_device_id lgm_pwm_of_match[] = { + { .compatible = "intel,lgm-pwm" }, + { } +}; +MODULE_DEVICE_TABLE(of, lgm_pwm_of_match); + +static struct platform_driver lgm_pwm_driver = { + .driver = { + .name = "intel-pwm", + .of_match_table = lgm_pwm_of_match, + }, + .probe = lgm_pwm_probe, + .remove = lgm_pwm_remove, +}; +module_platform_driver(lgm_pwm_driver); + +MODULE_LICENSE("GPL v2"); |