1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Copyright (C) 2015-2017 Pengutronix, Uwe Kleine-König <kernel@pengutronix.de> 4 */ 5 6 #include <linux/gpio/consumer.h> 7 #include <linux/module.h> 8 #include <linux/mod_devicetable.h> 9 #include <linux/platform_device.h> 10 11 #include <linux/delay.h> 12 13 #include "siox.h" 14 15 #define DRIVER_NAME "siox-gpio" 16 17 struct siox_gpio_ddata { 18 struct gpio_desc *din; 19 struct gpio_desc *dout; 20 struct gpio_desc *dclk; 21 struct gpio_desc *dld; 22 }; 23 24 static unsigned int siox_clkhigh_ns = 1000; 25 static unsigned int siox_loadhigh_ns; 26 static unsigned int siox_bytegap_ns; 27 28 static int siox_gpio_pushpull(struct siox_master *smaster, 29 size_t setbuf_len, const u8 setbuf[], 30 size_t getbuf_len, u8 getbuf[]) 31 { 32 struct siox_gpio_ddata *ddata = siox_master_get_devdata(smaster); 33 size_t i; 34 size_t cycles = max(setbuf_len, getbuf_len); 35 36 /* reset data and clock */ 37 gpiod_set_value_cansleep(ddata->dout, 0); 38 gpiod_set_value_cansleep(ddata->dclk, 0); 39 40 gpiod_set_value_cansleep(ddata->dld, 1); 41 ndelay(siox_loadhigh_ns); 42 gpiod_set_value_cansleep(ddata->dld, 0); 43 44 for (i = 0; i < cycles; ++i) { 45 u8 set = 0, get = 0; 46 size_t j; 47 48 if (i >= cycles - setbuf_len) 49 set = setbuf[i - (cycles - setbuf_len)]; 50 51 for (j = 0; j < 8; ++j) { 52 get <<= 1; 53 if (gpiod_get_value_cansleep(ddata->din)) 54 get |= 1; 55 56 /* DOUT is logically inverted */ 57 gpiod_set_value_cansleep(ddata->dout, !(set & 0x80)); 58 set <<= 1; 59 60 gpiod_set_value_cansleep(ddata->dclk, 1); 61 ndelay(siox_clkhigh_ns); 62 gpiod_set_value_cansleep(ddata->dclk, 0); 63 } 64 65 if (i < getbuf_len) 66 getbuf[i] = get; 67 68 ndelay(siox_bytegap_ns); 69 } 70 71 gpiod_set_value_cansleep(ddata->dld, 1); 72 ndelay(siox_loadhigh_ns); 73 gpiod_set_value_cansleep(ddata->dld, 0); 74 75 /* 76 * Resetting dout isn't necessary protocol wise, but it makes the 77 * signals more pretty because the dout level is deterministic between 78 * cycles. Note that this only affects dout between the master and the 79 * first siox device. dout for the later devices depend on the output of 80 * the previous siox device. 81 */ 82 gpiod_set_value_cansleep(ddata->dout, 0); 83 84 return 0; 85 } 86 87 static int siox_gpio_probe(struct platform_device *pdev) 88 { 89 struct device *dev = &pdev->dev; 90 struct siox_gpio_ddata *ddata; 91 int ret; 92 struct siox_master *smaster; 93 94 smaster = devm_siox_master_alloc(dev, sizeof(*ddata)); 95 if (!smaster) 96 return -ENOMEM; 97 98 platform_set_drvdata(pdev, smaster); 99 ddata = siox_master_get_devdata(smaster); 100 101 ddata->din = devm_gpiod_get(dev, "din", GPIOD_IN); 102 if (IS_ERR(ddata->din)) 103 return dev_err_probe(dev, PTR_ERR(ddata->din), 104 "Failed to get din GPIO\n"); 105 106 ddata->dout = devm_gpiod_get(dev, "dout", GPIOD_OUT_LOW); 107 if (IS_ERR(ddata->dout)) 108 return dev_err_probe(dev, PTR_ERR(ddata->dout), 109 "Failed to get dout GPIO\n"); 110 111 ddata->dclk = devm_gpiod_get(dev, "dclk", GPIOD_OUT_LOW); 112 if (IS_ERR(ddata->dclk)) 113 return dev_err_probe(dev, PTR_ERR(ddata->dclk), 114 "Failed to get dclk GPIO\n"); 115 116 ddata->dld = devm_gpiod_get(dev, "dld", GPIOD_OUT_LOW); 117 if (IS_ERR(ddata->dld)) 118 return dev_err_probe(dev, PTR_ERR(ddata->dld), 119 "Failed to get dld GPIO\n"); 120 121 smaster->pushpull = siox_gpio_pushpull; 122 /* XXX: determine automatically like spi does */ 123 smaster->busno = 0; 124 125 ret = devm_siox_master_register(dev, smaster); 126 if (ret) 127 return dev_err_probe(dev, ret, 128 "Failed to register siox master\n"); 129 130 return 0; 131 } 132 133 static const struct of_device_id siox_gpio_dt_ids[] = { 134 { .compatible = "eckelmann,siox-gpio", }, 135 { /* sentinel */ } 136 }; 137 MODULE_DEVICE_TABLE(of, siox_gpio_dt_ids); 138 139 static struct platform_driver siox_gpio_driver = { 140 .probe = siox_gpio_probe, 141 142 .driver = { 143 .name = DRIVER_NAME, 144 .of_match_table = siox_gpio_dt_ids, 145 }, 146 }; 147 module_platform_driver(siox_gpio_driver); 148 149 MODULE_AUTHOR("Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>"); 150 MODULE_DESCRIPTION("SIOX GPIO bus driver"); 151 MODULE_LICENSE("GPL v2"); 152 MODULE_ALIAS("platform:" DRIVER_NAME); 153