diff options
Diffstat (limited to 'drivers/gpio/gpio-max3191x.c')
| -rw-r--r-- | drivers/gpio/gpio-max3191x.c | 497 |
1 files changed, 497 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-max3191x.c b/drivers/gpio/gpio-max3191x.c new file mode 100644 index 000000000..b5b9cb1fd --- /dev/null +++ b/drivers/gpio/gpio-max3191x.c @@ -0,0 +1,497 @@ +/* + * gpio-max3191x.c - GPIO driver for Maxim MAX3191x industrial serializer + * + * Copyright (C) 2017 KUNBUS GmbH + * + * The MAX3191x makes 8 digital 24V inputs available via SPI. + * Multiple chips can be daisy-chained, the spec does not impose + * a limit on the number of chips and neither does this driver. + * + * Either of two modes is selectable: In 8-bit mode, only the state + * of the inputs is clocked out to achieve high readout speeds; + * In 16-bit mode, an additional status byte is clocked out with + * a CRC and indicator bits for undervoltage and overtemperature. + * The driver returns an error instead of potentially bogus data + * if any of these fault conditions occur. However it does allow + * readout of non-faulting chips in the same daisy-chain. + * + * MAX3191x supports four debounce settings and the driver is + * capable of configuring these differently for each chip in the + * daisy-chain. + * + * If the chips are hardwired to 8-bit mode ("modesel" pulled high), + * gpio-pisosr.c can be used alternatively to this driver. + * + * https://datasheets.maximintegrated.com/en/ds/MAX31910.pdf + * https://datasheets.maximintegrated.com/en/ds/MAX31911.pdf + * https://datasheets.maximintegrated.com/en/ds/MAX31912.pdf + * https://datasheets.maximintegrated.com/en/ds/MAX31913.pdf + * https://datasheets.maximintegrated.com/en/ds/MAX31953-MAX31963.pdf + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License (version 2) as + * published by the Free Software Foundation. + */ + +#include <linux/bitmap.h> +#include <linux/crc8.h> +#include <linux/gpio/consumer.h> +#include <linux/gpio/driver.h> +#include <linux/module.h> +#include <linux/spi/spi.h> + +enum max3191x_mode { + STATUS_BYTE_ENABLED, + STATUS_BYTE_DISABLED, +}; + +/** + * struct max3191x_chip - max3191x daisy-chain + * @gpio: GPIO controller struct + * @lock: protects read sequences + * @nchips: number of chips in the daisy-chain + * @mode: current mode, 0 for 16-bit, 1 for 8-bit; + * for simplicity, all chips in the daisy-chain are assumed + * to use the same mode + * @modesel_pins: GPIO pins to configure modesel of each chip + * @fault_pins: GPIO pins to detect fault of each chip + * @db0_pins: GPIO pins to configure debounce of each chip + * @db1_pins: GPIO pins to configure debounce of each chip + * @mesg: SPI message to perform a readout + * @xfer: SPI transfer used by @mesg + * @crc_error: bitmap signaling CRC error for each chip + * @overtemp: bitmap signaling overtemperature alarm for each chip + * @undervolt1: bitmap signaling undervoltage alarm for each chip + * @undervolt2: bitmap signaling undervoltage warning for each chip + * @fault: bitmap signaling assertion of @fault_pins for each chip + * @ignore_uv: whether to ignore undervoltage alarms; + * set by a device property if the chips are powered through + * 5VOUT instead of VCC24V, in which case they will constantly + * signal undervoltage; + * for simplicity, all chips in the daisy-chain are assumed + * to be powered the same way + */ +struct max3191x_chip { + struct gpio_chip gpio; + struct mutex lock; + u32 nchips; + enum max3191x_mode mode; + struct gpio_descs *modesel_pins; + struct gpio_descs *fault_pins; + struct gpio_descs *db0_pins; + struct gpio_descs *db1_pins; + struct spi_message mesg; + struct spi_transfer xfer; + unsigned long *crc_error; + unsigned long *overtemp; + unsigned long *undervolt1; + unsigned long *undervolt2; + unsigned long *fault; + bool ignore_uv; +}; + +#define MAX3191X_NGPIO 8 +#define MAX3191X_CRC8_POLYNOMIAL 0xa8 /* (x^5) + x^4 + x^2 + x^0 */ + +DECLARE_CRC8_TABLE(max3191x_crc8); + +static int max3191x_get_direction(struct gpio_chip *gpio, unsigned int offset) +{ + return 1; /* always in */ +} + +static int max3191x_direction_input(struct gpio_chip *gpio, unsigned int offset) +{ + return 0; +} + +static int max3191x_direction_output(struct gpio_chip *gpio, + unsigned int offset, int value) +{ + return -EINVAL; +} + +static void max3191x_set(struct gpio_chip *gpio, unsigned int offset, int value) +{ } + +static void max3191x_set_multiple(struct gpio_chip *gpio, unsigned long *mask, + unsigned long *bits) +{ } + +static unsigned int max3191x_wordlen(struct max3191x_chip *max3191x) +{ + return max3191x->mode == STATUS_BYTE_ENABLED ? 2 : 1; +} + +static int max3191x_readout_locked(struct max3191x_chip *max3191x) +{ + struct device *dev = max3191x->gpio.parent; + struct spi_device *spi = to_spi_device(dev); + int val, i, ot = 0, uv1 = 0; + + val = spi_sync(spi, &max3191x->mesg); + if (val) { + dev_err_ratelimited(dev, "SPI receive error %d\n", val); + return val; + } + + for (i = 0; i < max3191x->nchips; i++) { + if (max3191x->mode == STATUS_BYTE_ENABLED) { + u8 in = ((u8 *)max3191x->xfer.rx_buf)[i * 2]; + u8 status = ((u8 *)max3191x->xfer.rx_buf)[i * 2 + 1]; + + val = (status & 0xf8) != crc8(max3191x_crc8, &in, 1, 0); + __assign_bit(i, max3191x->crc_error, val); + if (val) + dev_err_ratelimited(dev, + "chip %d: CRC error\n", i); + + ot = (status >> 1) & 1; + __assign_bit(i, max3191x->overtemp, ot); + if (ot) + dev_err_ratelimited(dev, + "chip %d: overtemperature\n", i); + + if (!max3191x->ignore_uv) { + uv1 = !((status >> 2) & 1); + __assign_bit(i, max3191x->undervolt1, uv1); + if (uv1) + dev_err_ratelimited(dev, + "chip %d: undervoltage\n", i); + + val = !(status & 1); + __assign_bit(i, max3191x->undervolt2, val); + if (val && !uv1) + dev_warn_ratelimited(dev, + "chip %d: voltage warn\n", i); + } + } + + if (max3191x->fault_pins && !max3191x->ignore_uv) { + /* fault pin shared by all chips or per chip */ + struct gpio_desc *fault_pin = + (max3191x->fault_pins->ndescs == 1) + ? max3191x->fault_pins->desc[0] + : max3191x->fault_pins->desc[i]; + + val = gpiod_get_value_cansleep(fault_pin); + if (val < 0) { + dev_err_ratelimited(dev, + "GPIO read error %d\n", val); + return val; + } + __assign_bit(i, max3191x->fault, val); + if (val && !uv1 && !ot) + dev_err_ratelimited(dev, + "chip %d: fault\n", i); + } + } + + return 0; +} + +static bool max3191x_chip_is_faulting(struct max3191x_chip *max3191x, + unsigned int chipnum) +{ + /* without status byte the only diagnostic is the fault pin */ + if (!max3191x->ignore_uv && test_bit(chipnum, max3191x->fault)) + return true; + + if (max3191x->mode == STATUS_BYTE_DISABLED) + return false; + + return test_bit(chipnum, max3191x->crc_error) || + test_bit(chipnum, max3191x->overtemp) || + (!max3191x->ignore_uv && + test_bit(chipnum, max3191x->undervolt1)); +} + +static int max3191x_get(struct gpio_chip *gpio, unsigned int offset) +{ + struct max3191x_chip *max3191x = gpiochip_get_data(gpio); + int ret, chipnum, wordlen = max3191x_wordlen(max3191x); + u8 in; + + mutex_lock(&max3191x->lock); + ret = max3191x_readout_locked(max3191x); + if (ret) + goto out_unlock; + + chipnum = offset / MAX3191X_NGPIO; + if (max3191x_chip_is_faulting(max3191x, chipnum)) { + ret = -EIO; + goto out_unlock; + } + + in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen]; + ret = (in >> (offset % MAX3191X_NGPIO)) & 1; + +out_unlock: + mutex_unlock(&max3191x->lock); + return ret; +} + +static int max3191x_get_multiple(struct gpio_chip *gpio, unsigned long *mask, + unsigned long *bits) +{ + struct max3191x_chip *max3191x = gpiochip_get_data(gpio); + int ret, bit = 0, wordlen = max3191x_wordlen(max3191x); + + mutex_lock(&max3191x->lock); + ret = max3191x_readout_locked(max3191x); + if (ret) + goto out_unlock; + + while ((bit = find_next_bit(mask, gpio->ngpio, bit)) != gpio->ngpio) { + unsigned int chipnum = bit / MAX3191X_NGPIO; + unsigned long in, shift, index; + + if (max3191x_chip_is_faulting(max3191x, chipnum)) { + ret = -EIO; + goto out_unlock; + } + + in = ((u8 *)max3191x->xfer.rx_buf)[chipnum * wordlen]; + shift = round_down(bit % BITS_PER_LONG, MAX3191X_NGPIO); + index = bit / BITS_PER_LONG; + bits[index] &= ~(mask[index] & (0xff << shift)); + bits[index] |= mask[index] & (in << shift); /* copy bits */ + + bit = (chipnum + 1) * MAX3191X_NGPIO; /* go to next chip */ + } + +out_unlock: + mutex_unlock(&max3191x->lock); + return ret; +} + +static int max3191x_set_config(struct gpio_chip *gpio, unsigned int offset, + unsigned long config) +{ + struct max3191x_chip *max3191x = gpiochip_get_data(gpio); + u32 debounce, chipnum, db0_val, db1_val; + + if (pinconf_to_config_param(config) != PIN_CONFIG_INPUT_DEBOUNCE) + return -ENOTSUPP; + + if (!max3191x->db0_pins || !max3191x->db1_pins) + return -EINVAL; + + debounce = pinconf_to_config_argument(config); + switch (debounce) { + case 0: + db0_val = 0; + db1_val = 0; + break; + case 1 ... 25: + db0_val = 0; + db1_val = 1; + break; + case 26 ... 750: + db0_val = 1; + db1_val = 0; + break; + case 751 ... 3000: + db0_val = 1; + db1_val = 1; + break; + default: + return -EINVAL; + } + + if (max3191x->db0_pins->ndescs == 1) + chipnum = 0; /* all chips use the same pair of debounce pins */ + else + chipnum = offset / MAX3191X_NGPIO; /* per chip debounce pins */ + + mutex_lock(&max3191x->lock); + gpiod_set_value_cansleep(max3191x->db0_pins->desc[chipnum], db0_val); + gpiod_set_value_cansleep(max3191x->db1_pins->desc[chipnum], db1_val); + mutex_unlock(&max3191x->lock); + return 0; +} + +static void gpiod_set_array_single_value_cansleep(unsigned int ndescs, + struct gpio_desc **desc, + int value) +{ + int i, *values; + + values = kmalloc_array(ndescs, sizeof(*values), GFP_KERNEL); + if (!values) + return; + + for (i = 0; i < ndescs; i++) + values[i] = value; + + gpiod_set_array_value_cansleep(ndescs, desc, values); + kfree(values); +} + +static struct gpio_descs *devm_gpiod_get_array_optional_count( + struct device *dev, const char *con_id, + enum gpiod_flags flags, unsigned int expected) +{ + struct gpio_descs *descs; + int found = gpiod_count(dev, con_id); + + if (found == -ENOENT) + return NULL; + + if (found != expected && found != 1) { + dev_err(dev, "ignoring %s-gpios: found %d, expected %u or 1\n", + con_id, found, expected); + return NULL; + } + + descs = devm_gpiod_get_array_optional(dev, con_id, flags); + + if (IS_ERR(descs)) { + dev_err(dev, "failed to get %s-gpios: %ld\n", + con_id, PTR_ERR(descs)); + return NULL; + } + + return descs; +} + +static int max3191x_probe(struct spi_device *spi) +{ + struct device *dev = &spi->dev; + struct max3191x_chip *max3191x; + int n, ret; + + max3191x = devm_kzalloc(dev, sizeof(*max3191x), GFP_KERNEL); + if (!max3191x) + return -ENOMEM; + spi_set_drvdata(spi, max3191x); + + max3191x->nchips = 1; + device_property_read_u32(dev, "#daisy-chained-devices", + &max3191x->nchips); + + n = BITS_TO_LONGS(max3191x->nchips); + max3191x->crc_error = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL); + max3191x->undervolt1 = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL); + max3191x->undervolt2 = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL); + max3191x->overtemp = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL); + max3191x->fault = devm_kcalloc(dev, n, sizeof(long), GFP_KERNEL); + max3191x->xfer.rx_buf = devm_kcalloc(dev, max3191x->nchips, + 2, GFP_KERNEL); + if (!max3191x->crc_error || !max3191x->undervolt1 || + !max3191x->overtemp || !max3191x->undervolt2 || + !max3191x->fault || !max3191x->xfer.rx_buf) + return -ENOMEM; + + max3191x->modesel_pins = devm_gpiod_get_array_optional_count(dev, + "maxim,modesel", GPIOD_ASIS, max3191x->nchips); + max3191x->fault_pins = devm_gpiod_get_array_optional_count(dev, + "maxim,fault", GPIOD_IN, max3191x->nchips); + max3191x->db0_pins = devm_gpiod_get_array_optional_count(dev, + "maxim,db0", GPIOD_OUT_LOW, max3191x->nchips); + max3191x->db1_pins = devm_gpiod_get_array_optional_count(dev, + "maxim,db1", GPIOD_OUT_LOW, max3191x->nchips); + + max3191x->mode = device_property_read_bool(dev, "maxim,modesel-8bit") + ? STATUS_BYTE_DISABLED : STATUS_BYTE_ENABLED; + if (max3191x->modesel_pins) + gpiod_set_array_single_value_cansleep( + max3191x->modesel_pins->ndescs, + max3191x->modesel_pins->desc, max3191x->mode); + + max3191x->ignore_uv = device_property_read_bool(dev, + "maxim,ignore-undervoltage"); + + if (max3191x->db0_pins && max3191x->db1_pins && + max3191x->db0_pins->ndescs != max3191x->db1_pins->ndescs) { + dev_err(dev, "ignoring maxim,db*-gpios: array len mismatch\n"); + devm_gpiod_put_array(dev, max3191x->db0_pins); + devm_gpiod_put_array(dev, max3191x->db1_pins); + max3191x->db0_pins = NULL; + max3191x->db1_pins = NULL; + } + + max3191x->xfer.len = max3191x->nchips * max3191x_wordlen(max3191x); + spi_message_init_with_transfers(&max3191x->mesg, &max3191x->xfer, 1); + + max3191x->gpio.label = spi->modalias; + max3191x->gpio.owner = THIS_MODULE; + max3191x->gpio.parent = dev; + max3191x->gpio.base = -1; + max3191x->gpio.ngpio = max3191x->nchips * MAX3191X_NGPIO; + max3191x->gpio.can_sleep = true; + + max3191x->gpio.get_direction = max3191x_get_direction; + max3191x->gpio.direction_input = max3191x_direction_input; + max3191x->gpio.direction_output = max3191x_direction_output; + max3191x->gpio.set = max3191x_set; + max3191x->gpio.set_multiple = max3191x_set_multiple; + max3191x->gpio.get = max3191x_get; + max3191x->gpio.get_multiple = max3191x_get_multiple; + max3191x->gpio.set_config = max3191x_set_config; + + mutex_init(&max3191x->lock); + + ret = gpiochip_add_data(&max3191x->gpio, max3191x); + if (ret) { + mutex_destroy(&max3191x->lock); + return ret; + } + + return 0; +} + +static int max3191x_remove(struct spi_device *spi) +{ + struct max3191x_chip *max3191x = spi_get_drvdata(spi); + + gpiochip_remove(&max3191x->gpio); + mutex_destroy(&max3191x->lock); + + return 0; +} + +static int __init max3191x_register_driver(struct spi_driver *sdrv) +{ + crc8_populate_msb(max3191x_crc8, MAX3191X_CRC8_POLYNOMIAL); + return spi_register_driver(sdrv); +} + +#ifdef CONFIG_OF +static const struct of_device_id max3191x_of_id[] = { + { .compatible = "maxim,max31910" }, + { .compatible = "maxim,max31911" }, + { .compatible = "maxim,max31912" }, + { .compatible = "maxim,max31913" }, + { .compatible = "maxim,max31953" }, + { .compatible = "maxim,max31963" }, + { } +}; +MODULE_DEVICE_TABLE(of, max3191x_of_id); +#endif + +static const struct spi_device_id max3191x_spi_id[] = { + { "max31910" }, + { "max31911" }, + { "max31912" }, + { "max31913" }, + { "max31953" }, + { "max31963" }, + { } +}; +MODULE_DEVICE_TABLE(spi, max3191x_spi_id); + +static struct spi_driver max3191x_driver = { + .driver = { + .name = "max3191x", + .of_match_table = of_match_ptr(max3191x_of_id), + }, + .probe = max3191x_probe, + .remove = max3191x_remove, + .id_table = max3191x_spi_id, +}; +module_driver(max3191x_driver, max3191x_register_driver, spi_unregister_driver); + +MODULE_AUTHOR("Lukas Wunner <lukas@wunner.de>"); +MODULE_DESCRIPTION("GPIO driver for Maxim MAX3191x industrial serializer"); +MODULE_LICENSE("GPL v2"); |