达芬奇平台DM644X(ARM9, Linux-2.6.10)BSP之clock.c分析

--------------------------------------------本文系本站原创,欢迎转载!转载请注明出处:http:// zhiqiang0071.cublog.cn --------------------------------------------                                                   /* * linux/arch/arm/mach-davinci/clock.c * * TI DaVinci clock config file * * Copyright (C) 2006 Texas Instruments. * * ---------------------------------------------------------------------------- * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * *  You should have received a copy of the GNU General Public License *  along with this program; if not, write to the Free Software *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * ---------------------------------------------------------------------------- * */ /* 该文件中到程序实现了各模块PSC的管理，时钟的初始化、注册、获取以及使能等 */ /************************************************************************** * Included Files **************************************************************************/ #include linux/config.h> #include linux/kernel.h> #include linux/module.h> #include linux/init.h> #include linux/fs.h> #include linux/major.h> #include linux/root_dev.h> #include asm/setup.h> #include asm/semaphore.h> #include asm/hardware/clock.h> #include asm/io.h> #include asm/mach-types.h> #include asm/mach/arch.h> #include asm/mach/map.h> #include asm/arch/hardware.h> #include asm/arch/cpu.h> #include asm/arch/mux.h> #include "clock.h" #define PLL1_PLLM   __REG(0x01c40910) #define PLL2_PLLM   __REG(0x01c40D10) #define PTCMD       __REG(0x01C41120) #define PDSTAT      __REG(0x01C41200) #define PDCTL1      __REG(0x01C41304) #define EPCPR       __REG(0x01C41070) #define PTSTAT      __REG(0x01C41128) #define MDSTAT  IO_ADDRESS(0x01C41800) #define MDCTL   IO_ADDRESS(0x01C41A00) #define VDD3P3V_PWDN  __REG(0x01C40048) static LIST_HEAD(clocks);    // 链表头，用于管理所有到时钟结构体 static DECLARE_MUTEX(clocks_sem);    // 添加和删除时钟用到信号量，用来互斥 static DEFINE_RAW_SPINLOCK(clockfw_lock); static unsigned int commonrate; static unsigned int div_by_four; static unsigned int div_by_six; static unsigned int div_by_eight; static unsigned int armrate; static unsigned int fixedrate; /* * 正如下面英文解释所说的，board_setup_psc函数用于使能和禁止某个PSC域， * 共有两个域DSP和ARM,在include/asm-arm/arch-davinci/hardware.h * 中定义。如果要使用某个模块到功能，比如SPI，则必须先使用该函数，打开该 * 模块的电源和时钟，然后才可以设置其寄存器和操作。 */ /************************************** Routine: board_setup_psc Description:  Enable/Disable a PSC domain **************************************/ void board_setup_psc(unsigned int domain, unsigned int id, char enable) {     volatile unsigned int *mdstat = (unsigned int *)((int)MDSTAT + 4 * id);     volatile unsigned int *mdctl = (unsigned int *)((int)MDCTL + 4 * id);     if (enable) {         *mdctl |= 0x00000003;    /* Enable Module */     } else {         *mdctl &= 0xFFFFFFF2;    /* Disable Module */     }     if ((PDSTAT & 0x00000001) == 0) {         PDCTL1 |= 0x1;         PTCMD = (1  domain);         while ((((EPCPR >> domain) & 1) == 0)) ;         PDCTL1 |= 0x100;         while (!(((PTSTAT >> domain) & 1) == 0)) ;     } else {         PTCMD = (1  domain);         while (!(((PTSTAT >> domain) & 1) == 0)) ;     }     if (enable) {         while (!((*mdstat & 0x0000001F) == 0x3)) ;     } else {         while (!((*mdstat & 0x0000001F) == 0x2)) ;     } } /* * 获取时钟结构体指针 * 从链表中获取时钟结构体指针，比较时钟名（字符串），如果相同就返回该结构体指针 */ struct clk *clk_get(struct device *dev, const char *id) {     struct clk *p, *clk = ERR_PTR(-ENOENT);     down(&clocks_sem);     list_for_each_entry(p, &clocks, node) {         if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {             clk = p;             break;         }     }     up(&clocks_sem);     return clk; } /* 导出该符号，以便其它驱动程序调用 */ EXPORT_SYMBOL(clk_get); /* 将时钟结构体放回到链表中，以便其它驱动能够获得 */ void clk_put(struct clk *clk) {     if (clk && !IS_ERR(clk))         module_put(clk->owner);        // 减少模块使用计数,模块使用计数的介绍可参考本站转载的文章《Linux kernel-2.6 模块使用计数》 } EXPORT_SYMBOL(clk_put); /* 打开模块的电源和时钟 */ int __clk_enable(struct clk *clk) {     if (clk->flags & ALWAYS_ENABLED)    // 检查是否已经打开         return 0;     board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, clk->lpsc, 1);    // 1代表使能     return 0; } /* 关闭模块的电源和时钟 */ void __clk_disable(struct clk *clk) {     if (clk->usecount)    // 检查模块是否正在被使用         return;     board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, clk->lpsc, 0);    // 0代表关闭 } /* 减少时钟引用计数 */ void __clk_unuse(struct clk *clk) {     if (clk->usecount > 0) {         --clk->usecount;     } } /* 增加时钟引用计数 */ int __clk_use(struct clk *clk) {     int ret = 0;     clk->usecount++;     return ret; } /* __clk_enable函数的封装，其它驱动可调用。 */ int clk_enable(struct clk *clk) {     unsigned long flags;     int ret;     spin_lock_irqsave(&clockfw_lock, flags);    // 关中断和多CPU占用     ret = __clk_enable(clk);     spin_unlock_irqrestore(&clockfw_lock, flags);     if (davinci_pinmux_setup)             davinci_pinmux_setup(clk->lpsc);    /* 打开其引脚到模块功能，dm644x各模块到功能引脚大多和GPIO功能复用，                                                 故使用前要初始化，默认是模块功能一脚而非GPIO */     else         printk (KERN_WARNING "WARNING davinci_pinmux_setup "             "uninitialized\n");     return ret; } EXPORT_SYMBOL(clk_enable); /* __clk_disable函数的封装 */ void clk_disable(struct clk *clk) {     unsigned long flags;     spin_lock_irqsave(&clockfw_lock, flags);     __clk_disable(clk);     spin_unlock_irqrestore(&clockfw_lock, flags); } EXPORT_SYMBOL(clk_disable); /* __clk_use函数的封装 */ int clk_use(struct clk *clk) {     unsigned long flags;     int ret = 0;     spin_lock_irqsave(&clockfw_lock, flags);     ret = __clk_use(clk);     spin_unlock_irqrestore(&clockfw_lock, flags);     return ret; } EXPORT_SYMBOL(clk_use); /* __clk_unuse函数的封装 */ void clk_unuse(struct clk *clk) {     unsigned long flags;     spin_lock_irqsave(&clockfw_lock, flags);     __clk_unuse(clk);     spin_unlock_irqrestore(&clockfw_lock, flags); } EXPORT_SYMBOL(clk_unuse); /* 获取模块时钟的频率 */ unsigned long clk_get_rate(struct clk *clk) {     return *(clk->rate); } EXPORT_SYMBOL(clk_get_rate); /* 添加时钟到链表中 */ int clk_register(struct clk *clk) {     down(&clocks_sem);     list_add(&clk->node, &clocks);     up(&clocks_sem);     return 0; } EXPORT_SYMBOL(clk_register); /* 将时钟从链表中清除 */ void clk_unregister(struct clk *clk) {     down(&clocks_sem);     list_del(&clk->node);     up(&clocks_sem); } EXPORT_SYMBOL(clk_unregister); /* dm644x平台所有模块的时钟*/ static struct clk davinci_dm644x_clks[] = {     {         .name = "ARMCLK",    // 时钟名，ARM域的时钟         .rate = &armrate,         .lpsc = -1,         .flags = ALWAYS_ENABLED,     },     {         .name = "UART0",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_UART0,         .usecount = 1,     },     {         .name = "EMACCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_EMAC_WRAPPER,     },     {         .name = "I2CCLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_I2C,     },     {         .name = "IDECLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_ATA,     },     {         .name = "McBSPCLK0",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_McBSP0,     },     {         .name = "MMCSDCLK0",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_MMC_SD0,     },     {         .name = "SPICLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_SPI,     },     {         .name = "gpio",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_GPIO,     },     {         .name = "AEMIFCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_AEMIF,         .usecount = 1,     },     {         .name = "PWM0_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM0,     },     {         .name = "PWM1_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM1,     },     {         .name = "PWM2_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM2,     },     {         .name = "USBCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_USB,     }, }; /* dm6467平台所有模块的时钟*/ static struct clk davinci_dm6467_clks[] = {     {         .name = "ARMCLK",         .rate = &armrate,         .lpsc = -1,         .flags = ALWAYS_ENABLED,     },     {         .name = "UART0",         .rate = &fixedrate,         .lpsc = DAVINCI_DM646X_LPSC_UART0,         .usecount = 1,     },     {         .name = "UART1",         .rate = &fixedrate,         .lpsc = DAVINCI_DM646X_LPSC_UART1,         .usecount = 1,     },     {         .name = "UART2",         .rate = &fixedrate,         .lpsc = DAVINCI_DM646X_LPSC_UART2,         .usecount = 1,     },     {         .name = "EMACCLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_EMAC,     },     {         .name = "I2CCLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_I2C,     },     {         .name = "IDECLK",         .rate = &div_by_six,         .lpsc = DAVINCI_LPSC_ATA,     },     {         .name = "McASPCLK0",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_McASP0,     },     {         .name = "McASPCLK1",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_McASP1,     },     {         .name = "SPICLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_SPI,     },     {         .name = "AEMIFCLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_AEMIF,         .usecount = 1,     },     {         .name = "PWM0_CLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_PWM0,     },     {         .name = "PWM1_CLK",         .rate = &div_by_four,         .lpsc = DAVINCI_DM646X_LPSC_PWM1,     },     {         .name = "USBCLK",         .rate = &div_by_four,         .lpsc = DAVINCI_LPSC_USB,     }, }; /* dm355平台所有模块的时钟*/ static struct clk davinci_dm355_clks[] = {     {         .name = "ARMCLK",         .rate = &armrate,         .lpsc = -1,         .flags = ALWAYS_ENABLED,     },     {         .name = "UART0",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_UART0,         .usecount = 1,     },     {         .name = "UART1",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_UART1,         .usecount = 1,     },     {         .name = "UART2",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_UART2,         .usecount = 1,     },     {         .name = "EMACCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_EMAC_WRAPPER,     },     {         .name = "I2CCLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_I2C,     },     {         .name = "IDECLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_ATA,     },     {         .name = "McBSPCLK0",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_McBSP0,     },     {         .name = "McBSPCLK1",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_McBSP1,     },     {         .name = "MMCSDCLK0",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_MMC_SD0,     },     {         .name = "MMCSDCLK1",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_MMC_SD1,     },     {         .name = "SPICLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_SPI,     },     {         .name = "gpio",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_GPIO,     },     {         .name = "AEMIFCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_AEMIF,         .usecount = 1,     },     {         .name = "PWM0_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM0,     },     {         .name = "PWM1_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM1,     },     {         .name = "PWM2_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM2,     },     {         .name = "PWM3_CLK",         .rate = &fixedrate,         .lpsc = DAVINCI_LPSC_PWM3,     },     {         .name = "USBCLK",         .rate = &commonrate,         .lpsc = DAVINCI_LPSC_USB,     }, }; /* clk初始化，采用一个链表把所有到时钟结构体链接在一起，该链表的头是clocks */ void davinci_clk_init(void) {     struct clk *clkp;     static struct clk *board_clks;     int count = 0, num_clks;     if (cpu_is_davinci_dm355()) {    // dm355平台时钟初始化         /*          * FIXME          * We're assuming a 24MHz reference, but the DM355 also          * supports a 36MHz reference.          */         unsigned long postdiv;         /*          * Read the PLL1 POSTDIV register to determine if the post          * divider is /1 or /2          */         postdiv = (davinci_readl(DAVINCI_PLL_CNTRL0_BASE + 0x128)             & 0x1f) + 1;         fixedrate = 24000000;         armrate = (PLL1_PLLM + 1) * (fixedrate / (16 * postdiv));         commonrate = armrate / 2;         board_clks = davinci_dm355_clks;         num_clks = ARRAY_SIZE(davinci_dm355_clks);     } else if (cpu_is_davinci_dm6467()) {        // dm6467平台时钟初始化         fixedrate = 24000000;         div_by_four = ((PLL1_PLLM + 1) * 27000000) / 4;         div_by_six = ((PLL1_PLLM + 1) * 27000000) / 6;         div_by_eight = ((PLL1_PLLM + 1) * 27000000) / 8;         armrate = ((PLL1_PLLM + 1) * 27000000) / 2;         board_clks = davinci_dm6467_clks;         num_clks = ARRAY_SIZE(davinci_dm6467_clks);     } else {                                    // dm644X平台时钟初始化         fixedrate = 27000000;    // 平台输入频率，即晶振频率         armrate = (PLL1_PLLM + 1) * (fixedrate / 2);    // arm时钟，其为DSP时钟的一半         commonrate = armrate / 3;                // 其他时钟为DSP时钟的1/6，arm时钟的1/3         board_clks = davinci_dm644x_clks;         num_clks = ARRAY_SIZE(davinci_dm644x_clks);     }     for (clkp = board_clks; count  num_clks; count++, clkp++) {              clk_register(clkp);        // 将时钟注册到链表中         /* Turn on clocks that have been enabled in the          * table above */         if (clkp->usecount) {        // 如果该时钟已经被使用，则开启它             clk_enable(clkp);        // 使能该时钟         }     } } 本文来自ChinaUnix博客，如果查看原文请点：http://blog.chinaunix.net/u2/79779/showart_1356828.html