diff options
Diffstat (limited to 'drivers/iio/adc/aspeed_adc.c')
| -rw-r--r-- | drivers/iio/adc/aspeed_adc.c | 295 |
1 files changed, 295 insertions, 0 deletions
diff --git a/drivers/iio/adc/aspeed_adc.c b/drivers/iio/adc/aspeed_adc.c new file mode 100644 index 000000000000..62670cbfa2bb --- /dev/null +++ b/drivers/iio/adc/aspeed_adc.c @@ -0,0 +1,295 @@ +/* + * Aspeed AST2400/2500 ADC + * + * Copyright (C) 2017 Google, Inc. + * + * This program is free software; you can redistribute it and/or modify it + * under the terms and conditions of the GNU General Public License, + * version 2, as published by the Free Software Foundation. + * + */ + +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of_platform.h> +#include <linux/platform_device.h> +#include <linux/spinlock.h> +#include <linux/types.h> + +#include <linux/iio/iio.h> +#include <linux/iio/driver.h> + +#define ASPEED_RESOLUTION_BITS 10 +#define ASPEED_CLOCKS_PER_SAMPLE 12 + +#define ASPEED_REG_ENGINE_CONTROL 0x00 +#define ASPEED_REG_INTERRUPT_CONTROL 0x04 +#define ASPEED_REG_VGA_DETECT_CONTROL 0x08 +#define ASPEED_REG_CLOCK_CONTROL 0x0C +#define ASPEED_REG_MAX 0xC0 + +#define ASPEED_OPERATION_MODE_POWER_DOWN (0x0 << 1) +#define ASPEED_OPERATION_MODE_STANDBY (0x1 << 1) +#define ASPEED_OPERATION_MODE_NORMAL (0x7 << 1) + +#define ASPEED_ENGINE_ENABLE BIT(0) + +struct aspeed_adc_model_data { + const char *model_name; + unsigned int min_sampling_rate; // Hz + unsigned int max_sampling_rate; // Hz + unsigned int vref_voltage; // mV +}; + +struct aspeed_adc_data { + struct device *dev; + void __iomem *base; + spinlock_t clk_lock; + struct clk_hw *clk_prescaler; + struct clk_hw *clk_scaler; +}; + +#define ASPEED_CHAN(_idx, _data_reg_addr) { \ + .type = IIO_VOLTAGE, \ + .indexed = 1, \ + .channel = (_idx), \ + .address = (_data_reg_addr), \ + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) | \ + BIT(IIO_CHAN_INFO_SAMP_FREQ), \ +} + +static const struct iio_chan_spec aspeed_adc_iio_channels[] = { + ASPEED_CHAN(0, 0x10), + ASPEED_CHAN(1, 0x12), + ASPEED_CHAN(2, 0x14), + ASPEED_CHAN(3, 0x16), + ASPEED_CHAN(4, 0x18), + ASPEED_CHAN(5, 0x1A), + ASPEED_CHAN(6, 0x1C), + ASPEED_CHAN(7, 0x1E), + ASPEED_CHAN(8, 0x20), + ASPEED_CHAN(9, 0x22), + ASPEED_CHAN(10, 0x24), + ASPEED_CHAN(11, 0x26), + ASPEED_CHAN(12, 0x28), + ASPEED_CHAN(13, 0x2A), + ASPEED_CHAN(14, 0x2C), + ASPEED_CHAN(15, 0x2E), +}; + +static int aspeed_adc_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct aspeed_adc_data *data = iio_priv(indio_dev); + const struct aspeed_adc_model_data *model_data = + of_device_get_match_data(data->dev); + + switch (mask) { + case IIO_CHAN_INFO_RAW: + *val = readw(data->base + chan->address); + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + *val = model_data->vref_voltage; + *val2 = ASPEED_RESOLUTION_BITS; + return IIO_VAL_FRACTIONAL_LOG2; + + case IIO_CHAN_INFO_SAMP_FREQ: + *val = clk_get_rate(data->clk_scaler->clk) / + ASPEED_CLOCKS_PER_SAMPLE; + return IIO_VAL_INT; + + default: + return -EINVAL; + } +} + +static int aspeed_adc_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct aspeed_adc_data *data = iio_priv(indio_dev); + const struct aspeed_adc_model_data *model_data = + of_device_get_match_data(data->dev); + + switch (mask) { + case IIO_CHAN_INFO_SAMP_FREQ: + if (val < model_data->min_sampling_rate || + val > model_data->max_sampling_rate) + return -EINVAL; + + clk_set_rate(data->clk_scaler->clk, + val * ASPEED_CLOCKS_PER_SAMPLE); + return 0; + + case IIO_CHAN_INFO_SCALE: + case IIO_CHAN_INFO_RAW: + /* + * Technically, these could be written but the only reasons + * for doing so seem better handled in userspace. EPERM is + * returned to signal this is a policy choice rather than a + * hardware limitation. + */ + return -EPERM; + + default: + return -EINVAL; + } +} + +static int aspeed_adc_reg_access(struct iio_dev *indio_dev, + unsigned int reg, unsigned int writeval, + unsigned int *readval) +{ + struct aspeed_adc_data *data = iio_priv(indio_dev); + + if (!readval || reg % 4 || reg > ASPEED_REG_MAX) + return -EINVAL; + + *readval = readl(data->base + reg); + + return 0; +} + +static const struct iio_info aspeed_adc_iio_info = { + .driver_module = THIS_MODULE, + .read_raw = aspeed_adc_read_raw, + .write_raw = aspeed_adc_write_raw, + .debugfs_reg_access = aspeed_adc_reg_access, +}; + +static int aspeed_adc_probe(struct platform_device *pdev) +{ + struct iio_dev *indio_dev; + struct aspeed_adc_data *data; + const struct aspeed_adc_model_data *model_data; + struct resource *res; + const char *clk_parent_name; + int ret; + u32 adc_engine_control_reg_val; + + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*data)); + if (!indio_dev) + return -ENOMEM; + + data = iio_priv(indio_dev); + data->dev = &pdev->dev; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + data->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(data->base)) + return PTR_ERR(data->base); + + /* Register ADC clock prescaler with source specified by device tree. */ + spin_lock_init(&data->clk_lock); + clk_parent_name = of_clk_get_parent_name(pdev->dev.of_node, 0); + + data->clk_prescaler = clk_hw_register_divider( + &pdev->dev, "prescaler", clk_parent_name, 0, + data->base + ASPEED_REG_CLOCK_CONTROL, + 17, 15, 0, &data->clk_lock); + if (IS_ERR(data->clk_prescaler)) + return PTR_ERR(data->clk_prescaler); + + /* + * Register ADC clock scaler downstream from the prescaler. Allow rate + * setting to adjust the prescaler as well. + */ + data->clk_scaler = clk_hw_register_divider( + &pdev->dev, "scaler", "prescaler", + CLK_SET_RATE_PARENT, + data->base + ASPEED_REG_CLOCK_CONTROL, + 0, 10, 0, &data->clk_lock); + if (IS_ERR(data->clk_scaler)) { + ret = PTR_ERR(data->clk_scaler); + goto scaler_error; + } + + /* Start all channels in normal mode. */ + clk_prepare_enable(data->clk_scaler->clk); + adc_engine_control_reg_val = GENMASK(31, 16) | + ASPEED_OPERATION_MODE_NORMAL | ASPEED_ENGINE_ENABLE; + writel(adc_engine_control_reg_val, + data->base + ASPEED_REG_ENGINE_CONTROL); + + model_data = of_device_get_match_data(&pdev->dev); + indio_dev->name = model_data->model_name; + indio_dev->dev.parent = &pdev->dev; + indio_dev->info = &aspeed_adc_iio_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = aspeed_adc_iio_channels; + indio_dev->num_channels = ARRAY_SIZE(aspeed_adc_iio_channels); + + ret = iio_device_register(indio_dev); + if (ret) + goto iio_register_error; + + return 0; + +iio_register_error: + writel(ASPEED_OPERATION_MODE_POWER_DOWN, + data->base + ASPEED_REG_ENGINE_CONTROL); + clk_disable_unprepare(data->clk_scaler->clk); + clk_hw_unregister_divider(data->clk_scaler); + +scaler_error: + clk_hw_unregister_divider(data->clk_prescaler); + return ret; +} + +static int aspeed_adc_remove(struct platform_device *pdev) +{ + struct iio_dev *indio_dev = platform_get_drvdata(pdev); + struct aspeed_adc_data *data = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + writel(ASPEED_OPERATION_MODE_POWER_DOWN, + data->base + ASPEED_REG_ENGINE_CONTROL); + clk_disable_unprepare(data->clk_scaler->clk); + clk_hw_unregister_divider(data->clk_scaler); + clk_hw_unregister_divider(data->clk_prescaler); + + return 0; +} + +static const struct aspeed_adc_model_data ast2400_model_data = { + .model_name = "ast2400-adc", + .vref_voltage = 2500, // mV + .min_sampling_rate = 10000, + .max_sampling_rate = 500000, +}; + +static const struct aspeed_adc_model_data ast2500_model_data = { + .model_name = "ast2500-adc", + .vref_voltage = 1800, // mV + .min_sampling_rate = 1, + .max_sampling_rate = 1000000, +}; + +static const struct of_device_id aspeed_adc_matches[] = { + { .compatible = "aspeed,ast2400-adc", .data = &ast2400_model_data }, + { .compatible = "aspeed,ast2500-adc", .data = &ast2500_model_data }, + {}, +}; +MODULE_DEVICE_TABLE(of, aspeed_adc_matches); + +static struct platform_driver aspeed_adc_driver = { + .probe = aspeed_adc_probe, + .remove = aspeed_adc_remove, + .driver = { + .name = KBUILD_MODNAME, + .of_match_table = aspeed_adc_matches, + } +}; + +module_platform_driver(aspeed_adc_driver); + +MODULE_AUTHOR("Rick Altherr <raltherr@google.com>"); +MODULE_DESCRIPTION("Aspeed AST2400/2500 ADC Driver"); +MODULE_LICENSE("GPL"); |
