1 /* 2 * Driver for Atmel Flexcom 3 * 4 * Copyright (C) 2015 Atmel Corporation 5 * 6 * Author: Cyrille Pitchen <cyrille.pitchen@atmel.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope that it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 * more details. 16 * 17 * You should have received a copy of the GNU General Public License along with 18 * this program. If not, see <http://www.gnu.org/licenses/>. 19 */ 20 21 #include <linux/module.h> 22 #include <linux/types.h> 23 #include <linux/kernel.h> 24 #include <linux/platform_device.h> 25 #include <linux/of.h> 26 #include <linux/of_platform.h> 27 #include <linux/err.h> 28 #include <linux/io.h> 29 #include <linux/clk.h> 30 #include <dt-bindings/mfd/atmel-flexcom.h> 31 32 /* I/O register offsets */ 33 #define FLEX_MR 0x0 /* Mode Register */ 34 #define FLEX_VERSION 0xfc /* Version Register */ 35 36 /* Mode Register bit fields */ 37 #define FLEX_MR_OPMODE_OFFSET (0) /* Operating Mode */ 38 #define FLEX_MR_OPMODE_MASK (0x3 << FLEX_MR_OPMODE_OFFSET) 39 #define FLEX_MR_OPMODE(opmode) (((opmode) << FLEX_MR_OPMODE_OFFSET) & \ 40 FLEX_MR_OPMODE_MASK) 41 42 struct atmel_flexcom { 43 void __iomem *base; 44 u32 opmode; 45 struct clk *clk; 46 }; 47 48 static int atmel_flexcom_probe(struct platform_device *pdev) 49 { 50 struct device_node *np = pdev->dev.of_node; 51 struct resource *res; 52 struct atmel_flexcom *ddata; 53 int err; 54 55 ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL); 56 if (!ddata) 57 return -ENOMEM; 58 59 platform_set_drvdata(pdev, ddata); 60 61 err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode); 62 if (err) 63 return err; 64 65 if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART || 66 ddata->opmode > ATMEL_FLEXCOM_MODE_TWI) 67 return -EINVAL; 68 69 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 70 ddata->base = devm_ioremap_resource(&pdev->dev, res); 71 if (IS_ERR(ddata->base)) 72 return PTR_ERR(ddata->base); 73 74 ddata->clk = devm_clk_get(&pdev->dev, NULL); 75 if (IS_ERR(ddata->clk)) 76 return PTR_ERR(ddata->clk); 77 78 err = clk_prepare_enable(ddata->clk); 79 if (err) 80 return err; 81 82 /* 83 * Set the Operating Mode in the Mode Register: only the selected device 84 * is clocked. Hence, registers of the other serial devices remain 85 * inaccessible and are read as zero. Also the external I/O lines of the 86 * Flexcom are muxed to reach the selected device. 87 */ 88 writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR); 89 90 clk_disable_unprepare(ddata->clk); 91 92 return devm_of_platform_populate(&pdev->dev); 93 } 94 95 static const struct of_device_id atmel_flexcom_of_match[] = { 96 { .compatible = "atmel,sama5d2-flexcom" }, 97 { /* sentinel */ } 98 }; 99 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match); 100 101 #ifdef CONFIG_PM_SLEEP 102 static int atmel_flexcom_resume(struct device *dev) 103 { 104 struct atmel_flexcom *ddata = dev_get_drvdata(dev); 105 int err; 106 u32 val; 107 108 err = clk_prepare_enable(ddata->clk); 109 if (err) 110 return err; 111 112 val = FLEX_MR_OPMODE(ddata->opmode), 113 writel(val, ddata->base + FLEX_MR); 114 115 clk_disable_unprepare(ddata->clk); 116 117 return 0; 118 } 119 #endif 120 121 static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL, 122 atmel_flexcom_resume); 123 124 static struct platform_driver atmel_flexcom_driver = { 125 .probe = atmel_flexcom_probe, 126 .driver = { 127 .name = "atmel_flexcom", 128 .pm = &atmel_flexcom_pm_ops, 129 .of_match_table = atmel_flexcom_of_match, 130 }, 131 }; 132 133 module_platform_driver(atmel_flexcom_driver); 134 135 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>"); 136 MODULE_DESCRIPTION("Atmel Flexcom MFD driver"); 137 MODULE_LICENSE("GPL v2"); 138