/* * 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");