1 /* 2 * Copyright (C) 1999 ARM Limited 3 * Copyright (C) 2000 Deep Blue Solutions Ltd 4 * Copyright 2006-2007,2010 Freescale Semiconductor, Inc. All Rights Reserved. 5 * Copyright 2008 Juergen Beisert, kernel@pengutronix.de 6 * Copyright 2009 Ilya Yanok, Emcraft Systems Ltd, yanok@emcraft.com 7 * Copyright (C) 2011 Wolfram Sang, Pengutronix e.K. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 */ 14 15 #include <linux/io.h> 16 #include <linux/errno.h> 17 #include <linux/delay.h> 18 #include <linux/compiler.h> 19 #include <linux/export.h> 20 #include <linux/stmp_device.h> 21 22 #define STMP_MODULE_CLKGATE (1 << 30) 23 #define STMP_MODULE_SFTRST (1 << 31) 24 25 /* 26 * Clear the bit and poll it cleared. This is usually called with 27 * a reset address and mask being either SFTRST(bit 31) or CLKGATE 28 * (bit 30). 29 */ 30 static int stmp_clear_poll_bit(void __iomem *addr, u32 mask) 31 { 32 int timeout = 0x400; 33 34 writel(mask, addr + STMP_OFFSET_REG_CLR); 35 udelay(1); 36 while ((readl(addr) & mask) && --timeout) 37 /* nothing */; 38 39 return !timeout; 40 } 41 42 int stmp_reset_block(void __iomem *reset_addr) 43 { 44 int ret; 45 int timeout = 0x400; 46 47 /* clear and poll SFTRST */ 48 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST); 49 if (unlikely(ret)) 50 goto error; 51 52 /* clear CLKGATE */ 53 writel(STMP_MODULE_CLKGATE, reset_addr + STMP_OFFSET_REG_CLR); 54 55 /* set SFTRST to reset the block */ 56 writel(STMP_MODULE_SFTRST, reset_addr + STMP_OFFSET_REG_SET); 57 udelay(1); 58 59 /* poll CLKGATE becoming set */ 60 while ((!(readl(reset_addr) & STMP_MODULE_CLKGATE)) && --timeout) 61 /* nothing */; 62 if (unlikely(!timeout)) 63 goto error; 64 65 /* clear and poll SFTRST */ 66 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_SFTRST); 67 if (unlikely(ret)) 68 goto error; 69 70 /* clear and poll CLKGATE */ 71 ret = stmp_clear_poll_bit(reset_addr, STMP_MODULE_CLKGATE); 72 if (unlikely(ret)) 73 goto error; 74 75 return 0; 76 77 error: 78 pr_err("%s(%p): module reset timeout\n", __func__, reset_addr); 79 return -ETIMEDOUT; 80 } 81 EXPORT_SYMBOL(stmp_reset_block); 82