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 43 static int atmel_flexcom_probe(struct platform_device *pdev) 44 { 45 struct device_node *np = pdev->dev.of_node; 46 struct clk *clk; 47 struct resource *res; 48 void __iomem *base; 49 u32 opmode; 50 int err; 51 52 err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode); 53 if (err) 54 return err; 55 56 if (opmode < ATMEL_FLEXCOM_MODE_USART || 57 opmode > ATMEL_FLEXCOM_MODE_TWI) 58 return -EINVAL; 59 60 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 61 base = devm_ioremap_resource(&pdev->dev, res); 62 if (IS_ERR(base)) 63 return PTR_ERR(base); 64 65 clk = devm_clk_get(&pdev->dev, NULL); 66 if (IS_ERR(clk)) 67 return PTR_ERR(clk); 68 69 err = clk_prepare_enable(clk); 70 if (err) 71 return err; 72 73 /* 74 * Set the Operating Mode in the Mode Register: only the selected device 75 * is clocked. Hence, registers of the other serial devices remain 76 * inaccessible and are read as zero. Also the external I/O lines of the 77 * Flexcom are muxed to reach the selected device. 78 */ 79 writel(FLEX_MR_OPMODE(opmode), base + FLEX_MR); 80 81 clk_disable_unprepare(clk); 82 83 return of_platform_populate(np, NULL, NULL, &pdev->dev); 84 } 85 86 static const struct of_device_id atmel_flexcom_of_match[] = { 87 { .compatible = "atmel,sama5d2-flexcom" }, 88 { /* sentinel */ } 89 }; 90 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match); 91 92 static struct platform_driver atmel_flexcom_driver = { 93 .probe = atmel_flexcom_probe, 94 .driver = { 95 .name = "atmel_flexcom", 96 .of_match_table = atmel_flexcom_of_match, 97 }, 98 }; 99 100 module_platform_driver(atmel_flexcom_driver); 101 102 MODULE_AUTHOR("Cyrille Pitchen <cyrille.pitchen@atmel.com>"); 103 MODULE_DESCRIPTION("Atmel Flexcom MFD driver"); 104 MODULE_LICENSE("GPL v2"); 105