diff options
Diffstat (limited to 'drivers/pwm/pwm-axi-pwmgen.c')
| -rw-r--r-- | drivers/pwm/pwm-axi-pwmgen.c | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/drivers/pwm/pwm-axi-pwmgen.c b/drivers/pwm/pwm-axi-pwmgen.c new file mode 100644 index 000000000000..4337c8f5acf0 --- /dev/null +++ b/drivers/pwm/pwm-axi-pwmgen.c @@ -0,0 +1,324 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Analog Devices AXI PWM generator + * + * Copyright 2024 Analog Devices Inc. + * Copyright 2024 Baylibre SAS + * + * Device docs: https://analogdevicesinc.github.io/hdl/library/axi_pwm_gen/index.html + * + * Limitations: + * - The writes to registers for period and duty are shadowed until + * LOAD_CONFIG is written to AXI_PWMGEN_REG_RSTN, at which point + * they take effect. + * - Writing LOAD_CONFIG also has the effect of re-synchronizing all + * enabled channels, which could cause glitching on other channels. It + * is therefore expected that channels are assigned harmonic periods + * and all have a single user coordinating this. + * - Supports normal polarity. Does not support changing polarity. + * - On disable, the PWM output becomes low (inactive). + */ +#include <linux/bits.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/fpga/adi-axi-common.h> +#include <linux/io.h> +#include <linux/minmax.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/pwm.h> +#include <linux/regmap.h> +#include <linux/slab.h> + +#define AXI_PWMGEN_REG_ID 0x04 +#define AXI_PWMGEN_REG_SCRATCHPAD 0x08 +#define AXI_PWMGEN_REG_CORE_MAGIC 0x0C +#define AXI_PWMGEN_REG_RSTN 0x10 +#define AXI_PWMGEN_REG_RSTN_LOAD_CONFIG BIT(1) +#define AXI_PWMGEN_REG_RSTN_RESET BIT(0) +#define AXI_PWMGEN_REG_NPWM 0x14 +#define AXI_PWMGEN_REG_CONFIG 0x18 +#define AXI_PWMGEN_REG_CONFIG_FORCE_ALIGN BIT(1) +#define AXI_PWMGEN_CHX_PERIOD(ch) (0x40 + (4 * (ch))) +#define AXI_PWMGEN_CHX_DUTY(ch) (0x80 + (4 * (ch))) +#define AXI_PWMGEN_CHX_OFFSET(ch) (0xC0 + (4 * (ch))) +#define AXI_PWMGEN_REG_CORE_MAGIC_VAL 0x601A3471 /* Identification number to test during setup */ + +struct axi_pwmgen_ddata { + struct regmap *regmap; + unsigned long clk_rate_hz; +}; + +static const struct regmap_config axi_pwmgen_regmap_config = { + .reg_bits = 32, + .reg_stride = 4, + .val_bits = 32, + .max_register = 0xFC, +}; + +/* This represents a hardware configuration for one channel */ +struct axi_pwmgen_waveform { + u32 period_cnt; + u32 duty_cycle_cnt; + u32 duty_offset_cnt; +}; + +static struct axi_pwmgen_ddata *axi_pwmgen_ddata_from_chip(struct pwm_chip *chip) +{ + return pwmchip_get_drvdata(chip); +} + +static int axi_pwmgen_round_waveform_tohw(struct pwm_chip *chip, + struct pwm_device *pwm, + const struct pwm_waveform *wf, + void *_wfhw) +{ + struct axi_pwmgen_waveform *wfhw = _wfhw; + struct axi_pwmgen_ddata *ddata = axi_pwmgen_ddata_from_chip(chip); + int ret = 0; + + if (wf->period_length_ns == 0) { + *wfhw = (struct axi_pwmgen_waveform){ + .period_cnt = 0, + .duty_cycle_cnt = 0, + .duty_offset_cnt = 0, + }; + } else { + /* With ddata->clk_rate_hz < NSEC_PER_SEC this won't overflow. */ + wfhw->period_cnt = min_t(u64, + mul_u64_u32_div(wf->period_length_ns, ddata->clk_rate_hz, NSEC_PER_SEC), + U32_MAX); + + if (wfhw->period_cnt == 0) { + /* + * The specified period is too short for the hardware. + * So round up .period_cnt to 1 (i.e. the smallest + * possible period). With .duty_cycle and .duty_offset + * being less than or equal to .period, their rounded + * value must be 0. + */ + wfhw->period_cnt = 1; + wfhw->duty_cycle_cnt = 0; + wfhw->duty_offset_cnt = 0; + ret = 1; + } else { + wfhw->duty_cycle_cnt = min_t(u64, + mul_u64_u32_div(wf->duty_length_ns, ddata->clk_rate_hz, NSEC_PER_SEC), + U32_MAX); + wfhw->duty_offset_cnt = min_t(u64, + mul_u64_u32_div(wf->duty_offset_ns, ddata->clk_rate_hz, NSEC_PER_SEC), + U32_MAX); + } + } + + dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] @%lu -> PERIOD: %08x, DUTY: %08x, OFFSET: %08x\n", + pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns, + ddata->clk_rate_hz, wfhw->period_cnt, wfhw->duty_cycle_cnt, wfhw->duty_offset_cnt); + + return ret; +} + +static int axi_pwmgen_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm, + const void *_wfhw, struct pwm_waveform *wf) +{ + const struct axi_pwmgen_waveform *wfhw = _wfhw; + struct axi_pwmgen_ddata *ddata = axi_pwmgen_ddata_from_chip(chip); + + wf->period_length_ns = DIV64_U64_ROUND_UP((u64)wfhw->period_cnt * NSEC_PER_SEC, + ddata->clk_rate_hz); + + wf->duty_length_ns = DIV64_U64_ROUND_UP((u64)wfhw->duty_cycle_cnt * NSEC_PER_SEC, + ddata->clk_rate_hz); + + wf->duty_offset_ns = DIV64_U64_ROUND_UP((u64)wfhw->duty_offset_cnt * NSEC_PER_SEC, + ddata->clk_rate_hz); + + return 0; +} + +static int axi_pwmgen_write_waveform(struct pwm_chip *chip, + struct pwm_device *pwm, + const void *_wfhw) +{ + const struct axi_pwmgen_waveform *wfhw = _wfhw; + struct axi_pwmgen_ddata *ddata = axi_pwmgen_ddata_from_chip(chip); + struct regmap *regmap = ddata->regmap; + unsigned int ch = pwm->hwpwm; + int ret; + + ret = regmap_write(regmap, AXI_PWMGEN_CHX_PERIOD(ch), wfhw->period_cnt); + if (ret) + return ret; + + ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(ch), wfhw->duty_cycle_cnt); + if (ret) + return ret; + + ret = regmap_write(regmap, AXI_PWMGEN_CHX_OFFSET(ch), wfhw->duty_offset_cnt); + if (ret) + return ret; + + return regmap_write(regmap, AXI_PWMGEN_REG_RSTN, AXI_PWMGEN_REG_RSTN_LOAD_CONFIG); +} + +static int axi_pwmgen_read_waveform(struct pwm_chip *chip, + struct pwm_device *pwm, + void *_wfhw) +{ + struct axi_pwmgen_waveform *wfhw = _wfhw; + struct axi_pwmgen_ddata *ddata = axi_pwmgen_ddata_from_chip(chip); + struct regmap *regmap = ddata->regmap; + unsigned int ch = pwm->hwpwm; + int ret; + + ret = regmap_read(regmap, AXI_PWMGEN_CHX_PERIOD(ch), &wfhw->period_cnt); + if (ret) + return ret; + + ret = regmap_read(regmap, AXI_PWMGEN_CHX_DUTY(ch), &wfhw->duty_cycle_cnt); + if (ret) + return ret; + + ret = regmap_read(regmap, AXI_PWMGEN_CHX_OFFSET(ch), &wfhw->duty_offset_cnt); + if (ret) + return ret; + + if (wfhw->duty_cycle_cnt > wfhw->period_cnt) + wfhw->duty_cycle_cnt = wfhw->period_cnt; + + /* XXX: is this the actual behaviour of the hardware? */ + if (wfhw->duty_offset_cnt >= wfhw->period_cnt) { + wfhw->duty_cycle_cnt = 0; + wfhw->duty_offset_cnt = 0; + } + + return 0; +} + +static const struct pwm_ops axi_pwmgen_pwm_ops = { + .sizeof_wfhw = sizeof(struct axi_pwmgen_waveform), + .round_waveform_tohw = axi_pwmgen_round_waveform_tohw, + .round_waveform_fromhw = axi_pwmgen_round_waveform_fromhw, + .read_waveform = axi_pwmgen_read_waveform, + .write_waveform = axi_pwmgen_write_waveform, +}; + +static int axi_pwmgen_setup(struct regmap *regmap, struct device *dev) +{ + int ret; + u32 val; + + ret = regmap_read(regmap, AXI_PWMGEN_REG_CORE_MAGIC, &val); + if (ret) + return ret; + + if (val != AXI_PWMGEN_REG_CORE_MAGIC_VAL) + return dev_err_probe(dev, -ENODEV, + "failed to read expected value from register: got %08x, expected %08x\n", + val, AXI_PWMGEN_REG_CORE_MAGIC_VAL); + + ret = regmap_read(regmap, ADI_AXI_REG_VERSION, &val); + if (ret) + return ret; + + if (ADI_AXI_PCORE_VER_MAJOR(val) != 2) { + return dev_err_probe(dev, -ENODEV, "Unsupported peripheral version %u.%u.%u\n", + ADI_AXI_PCORE_VER_MAJOR(val), + ADI_AXI_PCORE_VER_MINOR(val), + ADI_AXI_PCORE_VER_PATCH(val)); + } + + /* Enable the core */ + ret = regmap_clear_bits(regmap, AXI_PWMGEN_REG_RSTN, AXI_PWMGEN_REG_RSTN_RESET); + if (ret) + return ret; + + /* + * Enable force align so that changes to PWM period and duty cycle take + * effect immediately. Otherwise, the effect of the change is delayed + * until the period of all channels run out, which can be long after the + * apply function returns. + */ + ret = regmap_set_bits(regmap, AXI_PWMGEN_REG_CONFIG, AXI_PWMGEN_REG_CONFIG_FORCE_ALIGN); + if (ret) + return ret; + + ret = regmap_read(regmap, AXI_PWMGEN_REG_NPWM, &val); + if (ret) + return ret; + + /* Return the number of PWMs */ + return val; +} + +static int axi_pwmgen_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct regmap *regmap; + struct pwm_chip *chip; + struct axi_pwmgen_ddata *ddata; + struct clk *clk; + void __iomem *io_base; + int ret; + + io_base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(io_base)) + return PTR_ERR(io_base); + + regmap = devm_regmap_init_mmio(dev, io_base, &axi_pwmgen_regmap_config); + if (IS_ERR(regmap)) + return dev_err_probe(dev, PTR_ERR(regmap), + "failed to init register map\n"); + + ret = axi_pwmgen_setup(regmap, dev); + if (ret < 0) + return ret; + + chip = devm_pwmchip_alloc(dev, ret, sizeof(*ddata)); + if (IS_ERR(chip)) + return PTR_ERR(chip); + ddata = pwmchip_get_drvdata(chip); + ddata->regmap = regmap; + + clk = devm_clk_get_enabled(dev, NULL); + if (IS_ERR(clk)) + return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n"); + + ret = devm_clk_rate_exclusive_get(dev, clk); + if (ret) + return dev_err_probe(dev, ret, "failed to get exclusive rate\n"); + + ddata->clk_rate_hz = clk_get_rate(clk); + if (!ddata->clk_rate_hz || ddata->clk_rate_hz > NSEC_PER_SEC) + return dev_err_probe(dev, -EINVAL, + "Invalid clock rate: %lu\n", ddata->clk_rate_hz); + + chip->ops = &axi_pwmgen_pwm_ops; + chip->atomic = true; + + ret = devm_pwmchip_add(dev, chip); + if (ret) + return dev_err_probe(dev, ret, "could not add PWM chip\n"); + + return 0; +} + +static const struct of_device_id axi_pwmgen_ids[] = { + { .compatible = "adi,axi-pwmgen-2.00.a" }, + { } +}; +MODULE_DEVICE_TABLE(of, axi_pwmgen_ids); + +static struct platform_driver axi_pwmgen_driver = { + .driver = { + .name = "axi-pwmgen", + .of_match_table = axi_pwmgen_ids, + }, + .probe = axi_pwmgen_probe, +}; +module_platform_driver(axi_pwmgen_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Sergiu Cuciurean <sergiu.cuciurean@analog.com>"); +MODULE_AUTHOR("Trevor Gamblin <tgamblin@baylibre.com>"); +MODULE_DESCRIPTION("Driver for the Analog Devices AXI PWM generator"); |