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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 | // SPDX-License-Identifier: GPL-2.0+ // // Gateworks I2C PLD GPIO expander // // Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org> // // Based on code and know-how from the OpenWrt driver: // Copyright (C) 2009 Gateworks Corporation // Authors: Chris Lang, Imre Kaloz #include <linux/bits.h> #include <linux/kernel.h> #include <linux/slab.h> #include <linux/gpio/driver.h> #include <linux/i2c.h> #include <linux/module.h> /** * struct gw_pld - State container for Gateworks PLD * @chip: GPIO chip instance * @client: I2C client * @out: shadow register for the output bute */ struct gw_pld { struct gpio_chip chip; struct i2c_client *client; u8 out; }; /* * The Gateworks I2C PLD chip only expose one read and one write register. * Writing a "one" bit (to match the reset state) lets that pin be used as an * input. It is an open-drain model. */ static int gw_pld_input8(struct gpio_chip *gc, unsigned offset) { struct gw_pld *gw = gpiochip_get_data(gc); gw->out |= BIT(offset); return i2c_smbus_write_byte(gw->client, gw->out); } static int gw_pld_get8(struct gpio_chip *gc, unsigned offset) { struct gw_pld *gw = gpiochip_get_data(gc); s32 val; val = i2c_smbus_read_byte(gw->client); return (val < 0) ? 0 : !!(val & BIT(offset)); } static int gw_pld_output8(struct gpio_chip *gc, unsigned offset, int value) { struct gw_pld *gw = gpiochip_get_data(gc); if (value) gw->out |= BIT(offset); else gw->out &= ~BIT(offset); return i2c_smbus_write_byte(gw->client, gw->out); } static void gw_pld_set8(struct gpio_chip *gc, unsigned offset, int value) { gw_pld_output8(gc, offset, value); } static int gw_pld_probe(struct i2c_client *client) { struct device *dev = &client->dev; struct gw_pld *gw; int ret; gw = devm_kzalloc(dev, sizeof(*gw), GFP_KERNEL); if (!gw) return -ENOMEM; gw->chip.base = -1; gw->chip.can_sleep = true; gw->chip.parent = dev; gw->chip.owner = THIS_MODULE; gw->chip.label = dev_name(dev); gw->chip.ngpio = 8; gw->chip.direction_input = gw_pld_input8; gw->chip.get = gw_pld_get8; gw->chip.direction_output = gw_pld_output8; gw->chip.set = gw_pld_set8; gw->client = client; /* * The Gateworks I2C PLD chip does not properly send the acknowledge * bit at all times, but we can still use the standard i2c_smbus * functions by simply ignoring this bit. */ client->flags |= I2C_M_IGNORE_NAK; gw->out = 0xFF; i2c_set_clientdata(client, gw); ret = devm_gpiochip_add_data(dev, &gw->chip, gw); if (ret) return ret; dev_info(dev, "registered Gateworks PLD GPIO device\n"); return 0; } static const struct i2c_device_id gw_pld_id[] = { { "gw-pld", }, { } }; MODULE_DEVICE_TABLE(i2c, gw_pld_id); static const struct of_device_id gw_pld_dt_ids[] = { { .compatible = "gateworks,pld-gpio", }, { }, }; MODULE_DEVICE_TABLE(of, gw_pld_dt_ids); static struct i2c_driver gw_pld_driver = { .driver = { .name = "gw_pld", .of_match_table = gw_pld_dt_ids, }, .probe = gw_pld_probe, .id_table = gw_pld_id, }; module_i2c_driver(gw_pld_driver); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>"); |