RTEMS-libbsd 实现beaglebone black USB驱动

libbsd是移植Freebsd的代码库，因此包含了USB的协议栈部分，因此我们要做的就是移植USB底层驱动程序。

Beaglebone black 的AM335x处理器采用的是musb otg的设备管理模式，因此需要musb的驱动程序。下图是Freebsd关于AM335x的驱动程序源文件：

对于USB驱动有关的就是am335x_musb.c以及am335x_usbss.c文件。

am335x_usbss.c文件是对于AM335的USB sub system的驱动文件，包括对物理层的一些驱动，比如使能USB时钟，查询USB硬件版本号等。

am335x_usbss.c：

/*-* Copyright (c) 2013 Oleksandr Tymoshenko <gonzo@freebsd.org>** Redistribution and use in source and binary forms, with or without* modification, are permitted provided that the following conditions* are met:* 1. Redistributions of source code must retain the above copyright*    notice, this list of conditions and the following disclaimer.* 2. Redistributions in binary form must reproduce the above copyright*    notice, this list of conditions and the following disclaimer in the*    documentation and/or other materials provided with the distribution.** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF* SUCH DAMAGE.*/#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>#include <dev/fdt/simplebus.h>
#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>#include <dev/usb/usb_core.h>
#include <dev/usb/usb_busdma.h>
#include <dev/usb/usb_process.h>
#include <dev/usb/usb_util.h>#include <dev/usb/usb_controller.h>
#include <dev/usb/usb_bus.h>
#include <dev/usb/controller/musb_otg.h>
#include <dev/usb/usb_debug.h>#include <sys/rman.h>#include <arm/ti/ti_prcm.h>
#include <arm/ti/ti_scm.h>
#include <arm/ti/am335x/am335x_scm.h>#define  AM335X_USB_PORTS    2#define    USBSS_REVREG        0x00
#define USBSS_SYSCONFIG     0x10
#define     USBSS_SYSCONFIG_SRESET      1#define USBCTRL_REV        0x00
#define USBCTRL_CTRL        0x14
#define USBCTRL_STAT        0x18
#define USBCTRL_IRQ_STAT0   0x30
#define     IRQ_STAT0_RXSHIFT   16
#define     IRQ_STAT0_TXSHIFT   0
#define USBCTRL_IRQ_STAT1   0x34
#define     IRQ_STAT1_DRVVBUS   (1 << 8)
#define USBCTRL_INTEN_SET0  0x38
#define USBCTRL_INTEN_SET1  0x3C
#define     USBCTRL_INTEN_USB_ALL   0x1ff
#define     USBCTRL_INTEN_USB_SOF   (1 << 3)
#define USBCTRL_INTEN_CLR0  0x40
#define USBCTRL_INTEN_CLR1  0x44
#define USBCTRL_UTMI        0xE0
#define     USBCTRL_UTMI_FSDATAEXT      (1 << 1)
#define USBCTRL_MODE        0xE8
#define     USBCTRL_MODE_IDDIG      (1 << 8)
#define     USBCTRL_MODE_IDDIGMUX       (1 << 7)#define   USBSS_WRITE4(sc, reg, val)      \bus_write_4((sc)->sc_mem_res, (reg), (val))
#define USBSS_READ4(sc, reg)            \bus_read_4((sc)->sc_mem_res, (reg))static device_probe_t usbss_probe;
static device_attach_t usbss_attach;
static device_detach_t usbss_detach;struct usbss_softc {struct simplebus_softc  simplebus_sc;struct resource        *sc_mem_res;int         sc_mem_rid;
};static int
usbss_probe(device_t dev)
{if (!ofw_bus_status_okay(dev))return (ENXIO);if (!ofw_bus_is_compatible(dev, "ti,am33xx-usb"))return (ENXIO);device_set_desc(dev, "TI AM33xx integrated USB OTG controller");return (BUS_PROBE_DEFAULT);
}static int
usbss_attach(device_t dev)
{struct usbss_softc *sc = device_get_softc(dev);int i;uint32_t rev;phandle_t node;/* Request the memory resources */sc->sc_mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY,&sc->sc_mem_rid, RF_ACTIVE);if (sc->sc_mem_res == NULL) {device_printf(dev,"Error: could not allocate mem resources\n");return (ENXIO);}/* Enable device clocks. */ti_prcm_clk_enable(MUSB0_CLK);/** Reset USBSS, USB0 and USB1.* The registers of USB subsystem must not be accessed while the* reset pulse is active (200ns).*/USBSS_WRITE4(sc, USBSS_SYSCONFIG, USBSS_SYSCONFIG_SRESET);DELAY(100);i = 10;while (USBSS_READ4(sc, USBSS_SYSCONFIG) & USBSS_SYSCONFIG_SRESET) {DELAY(100);if (i-- == 0) {device_printf(dev, "reset timeout.\n");return (ENXIO);}}/* Read the module revision. */rev = USBSS_READ4(sc, USBSS_REVREG);device_printf(dev, "TI AM335X USBSS v%d.%d.%d\n",(rev >> 8) & 7, (rev >> 6) & 3, rev & 63);node = ofw_bus_get_node(dev);if (node == -1) {usbss_detach(dev);return (ENXIO);}simplebus_init(dev, node);/** Allow devices to identify.*/bus_generic_probe(dev);/** Now walk the OFW tree and attach top-level devices.*/for (node = OF_child(node); node > 0; node = OF_peer(node))simplebus_add_device(dev, node, 0, NULL, -1, NULL);return (bus_generic_attach(dev));
}static int
usbss_detach(device_t dev)
{struct usbss_softc *sc = device_get_softc(dev);/* Free resources if any */if (sc->sc_mem_res)bus_release_resource(dev, SYS_RES_MEMORY, sc->sc_mem_rid,sc->sc_mem_res);/* during module unload there are lots of children leftover */device_delete_children(dev);return (0);
}static device_method_t usbss_methods[] = {/* Device interface */DEVMETHOD(device_probe, usbss_probe),DEVMETHOD(device_attach, usbss_attach),DEVMETHOD(device_detach, usbss_detach),DEVMETHOD(device_suspend, bus_generic_suspend),DEVMETHOD(device_resume, bus_generic_resume),DEVMETHOD(device_shutdown, bus_generic_shutdown),DEVMETHOD_END
};DEFINE_CLASS_1(usbss, usbss_driver, usbss_methods,sizeof(struct usbss_softc), simplebus_driver);
static devclass_t usbss_devclass;
DRIVER_MODULE(usbss, simplebus, usbss_driver, usbss_devclass, 0, 0);
MODULE_DEPEND(usbss, usb, 1, 1, 1);

该驱动源码中对于usb时钟的使能采用函数：

ti_prcm_clk_enable(MUSB0_CLK);

该函数还调用了ti_prcm.c 和ti_scm.c 中的函数实现，prcm是power control module，是电源控制模块，scm是system control module，这两个模块也是需要移植的，由于比较简单，在此不在赘述。

然后在usbss文件最后的模块依赖部分：

DEFINE_CLASS_1(usbss, usbss_driver, usbss_methods,sizeof(struct usbss_softc), simplebus_driver);
static devclass_t usbss_devclass;
DRIVER_MODULE(usbss, simplebus, usbss_driver, usbss_devclass, 0, 0);
MODULE_DEPEND(usbss, usb, 1, 1, 1);

DRIVER_MODULE中usbss是挂载到simplebus总线上，在FreeBSD上可以这样实现，因此其包含simplebus总线，但在rtems中，并不支持simplebus，目前rtems只支持nexus总线，因此需要将simplebus改成nexus即可。

接下来移植am335x_musb.c，该驱动文件非常重要，包含了对musb的驱动，是整个usb驱动的关键部分，接下来分析该文件：

am335x_musb.c:

/*-* Copyright (c) 2013 Oleksandr Tymoshenko <gonzo@freebsd.org>** Redistribution and use in source and binary forms, with or without* modification, are permitted provided that the following conditions* are met:* 1. Redistributions of source code must retain the above copyright*    notice, this list of conditions and the following disclaimer.* 2. Redistributions in binary form must reproduce the above copyright*    notice, this list of conditions and the following disclaimer in the*    documentation and/or other materials provided with the distribution.** THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF* SUCH DAMAGE.*/#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");#include <sys/stdint.h>
#include <sys/stddef.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/types.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/bus.h>
#include <sys/module.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/sysctl.h>
#include <sys/sx.h>
#include <sys/unistd.h>
#include <sys/callout.h>
#include <sys/malloc.h>
#include <sys/priv.h>#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>#include <dev/usb/usb.h>
#include <dev/usb/usbdi.h>#include <dev/usb/usb_core.h>
#include <dev/usb/usb_busdma.h>
#include <dev/usb/usb_process.h>
#include <dev/usb/usb_util.h>#define  USB_DEBUG_VAR usbssdebug#include <dev/usb/usb_controller.h>
#include <dev/usb/usb_bus.h>
#include <dev/usb/controller/musb_otg.h>
#include <dev/usb/usb_debug.h>#include <sys/rman.h>#include <arm/ti/ti_prcm.h>
#include <arm/ti/ti_scm.h>
#include <arm/ti/am335x/am335x_scm.h>#define USBCTRL_REV      0x00
#define USBCTRL_CTRL        0x14
#define USBCTRL_STAT        0x18
#define USBCTRL_IRQ_STAT0   0x30
#define     IRQ_STAT0_RXSHIFT   16
#define     IRQ_STAT0_TXSHIFT   0
#define USBCTRL_IRQ_STAT1   0x34
#define     IRQ_STAT1_DRVVBUS   (1 << 8)
#define USBCTRL_INTEN_SET0  0x38
#define USBCTRL_INTEN_SET1  0x3C
#define     USBCTRL_INTEN_USB_ALL   0x1ff
#define     USBCTRL_INTEN_USB_SOF   (1 << 3)
#define USBCTRL_INTEN_CLR0  0x40
#define USBCTRL_INTEN_CLR1  0x44
#define USBCTRL_UTMI        0xE0
#define     USBCTRL_UTMI_FSDATAEXT      (1 << 1)
#define USBCTRL_MODE        0xE8
#define     USBCTRL_MODE_IDDIG      (1 << 8)
#define     USBCTRL_MODE_IDDIGMUX       (1 << 7)/* USBSS resource + 2 MUSB ports */#define RES_USBCORE   0
#define RES_USBCTRL 1#define    USB_WRITE4(sc, idx, reg, val)   do {        \bus_write_4((sc)->sc_mem_res[idx], (reg), (val));   \
} while (0)#define  USB_READ4(sc, idx, reg) bus_read_4((sc)->sc_mem_res[idx], (reg))#define  USBCTRL_WRITE4(sc, reg, val)    \USB_WRITE4((sc), RES_USBCTRL, (reg), (val))
#define USBCTRL_READ4(sc, reg)      \USB_READ4((sc), RES_USBCTRL, (reg))static struct resource_spec am335x_musbotg_mem_spec[] = {{ SYS_RES_MEMORY,   0,  RF_ACTIVE },{ SYS_RES_MEMORY,   1,  RF_ACTIVE },{ -1,               0,  0 }
};#ifdef USB_DEBUG
static int usbssdebug = 0;static SYSCTL_NODE(_hw_usb, OID_AUTO, am335x_usbss, CTLFLAG_RW, 0, "AM335x USBSS");
SYSCTL_INT(_hw_usb_am335x_usbss, OID_AUTO, debug, CTLFLAG_RW,&usbssdebug, 0, "Debug level");
#endifstatic device_probe_t musbotg_probe;
static device_attach_t musbotg_attach;
static device_detach_t musbotg_detach;struct musbotg_super_softc {struct musbotg_softc  sc_otg;struct resource      *sc_mem_res[2];int          sc_irq_rid;
};static void
musbotg_vbus_poll(struct musbotg_super_softc *sc)
{uint32_t stat;if (sc->sc_otg.sc_mode == MUSB2_DEVICE_MODE)musbotg_vbus_interrupt(&sc->sc_otg, 1);else {stat = USBCTRL_READ4(sc, USBCTRL_STAT);musbotg_vbus_interrupt(&sc->sc_otg, stat & 1);}
}/** Arg to musbotg_clocks_on and musbot_clocks_off is* a uint32_t * pointing to the SCM register offset.*/
static uint32_t USB_CTRL[] = {SCM_USB_CTRL0, SCM_USB_CTRL1};static void
musbotg_clocks_on(void *arg)
{struct musbotg_softc *sc;uint32_t c, reg;sc = arg;reg = USB_CTRL[sc->sc_id];ti_scm_reg_read_4(reg, &c);c &= ~3; /* Enable power */c |= 1 << 19; /* VBUS detect enable */c |= 1 << 20; /* Session end enable */ti_scm_reg_write_4(reg, c);
}static void
musbotg_clocks_off(void *arg)
{struct musbotg_softc *sc;uint32_t c, reg;sc = arg;reg = USB_CTRL[sc->sc_id];/* Disable power to PHY */ti_scm_reg_read_4(reg, &c);ti_scm_reg_write_4(reg, c | 3);
}static void
musbotg_ep_int_set(struct musbotg_softc *sc, int ep, int on)
{struct musbotg_super_softc *ssc = sc->sc_platform_data;uint32_t epmask;epmask = ((1 << ep) << IRQ_STAT0_RXSHIFT);epmask |= ((1 << ep) << IRQ_STAT0_TXSHIFT);if (on)USBCTRL_WRITE4(ssc, USBCTRL_INTEN_SET0, epmask);elseUSBCTRL_WRITE4(ssc, USBCTRL_INTEN_CLR0, epmask);
}static void
musbotg_wrapper_interrupt(void *arg)
{struct musbotg_softc *sc = arg;struct musbotg_super_softc *ssc = sc->sc_platform_data;uint32_t stat, stat0, stat1;stat = USBCTRL_READ4(ssc, USBCTRL_STAT);stat0 = USBCTRL_READ4(ssc, USBCTRL_IRQ_STAT0);stat1 = USBCTRL_READ4(ssc, USBCTRL_IRQ_STAT1);if (stat0)USBCTRL_WRITE4(ssc, USBCTRL_IRQ_STAT0, stat0);if (stat1)USBCTRL_WRITE4(ssc, USBCTRL_IRQ_STAT1, stat1);DPRINTFN(4, "port%d: stat0=%08x stat1=%08x, stat=%08x\n",sc->sc_id, stat0, stat1, stat);if (stat1 & IRQ_STAT1_DRVVBUS)musbotg_vbus_interrupt(sc, stat & 1);musbotg_interrupt(arg, ((stat0 >> 16) & 0xffff),stat0 & 0xffff, stat1 & 0xff);
}static int
musbotg_probe(device_t dev)
{if (!ofw_bus_status_okay(dev))return (ENXIO);if (!ofw_bus_is_compatible(dev, "ti,musb-am33xx"))return (ENXIO);device_set_desc(dev, "TI AM33xx integrated USB OTG controller");return (BUS_PROBE_DEFAULT);
}static int
musbotg_attach(device_t dev)
{struct musbotg_super_softc *sc = device_get_softc(dev);char mode[16];int err;uint32_t reg;sc->sc_otg.sc_id = device_get_unit(dev);/* Request the memory resources */err = bus_alloc_resources(dev, am335x_musbotg_mem_spec,sc->sc_mem_res);if (err) {device_printf(dev,"Error: could not allocate mem resources\n");return (ENXIO);}/* Request the IRQ resources */sc->sc_otg.sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ,&sc->sc_irq_rid, RF_ACTIVE);if (sc->sc_otg.sc_irq_res == NULL) {device_printf(dev,"Error: could not allocate irq resources\n");return (ENXIO);}/* setup MUSB OTG USB controller interface softc */sc->sc_otg.sc_clocks_on = &musbotg_clocks_on;sc->sc_otg.sc_clocks_off = &musbotg_clocks_off;sc->sc_otg.sc_clocks_arg = &sc->sc_otg;sc->sc_otg.sc_ep_int_set = musbotg_ep_int_set;/* initialise some bus fields */sc->sc_otg.sc_bus.parent = dev;sc->sc_otg.sc_bus.devices = sc->sc_otg.sc_devices;sc->sc_otg.sc_bus.devices_max = MUSB2_MAX_DEVICES;sc->sc_otg.sc_bus.dma_bits = 32;/* get all DMA memory */if (usb_bus_mem_alloc_all(&sc->sc_otg.sc_bus,USB_GET_DMA_TAG(dev), NULL)) {device_printf(dev,"Failed allocate bus mem for musb\n");return (ENOMEM);}sc->sc_otg.sc_io_res = sc->sc_mem_res[RES_USBCORE];sc->sc_otg.sc_io_tag =rman_get_bustag(sc->sc_otg.sc_io_res);sc->sc_otg.sc_io_hdl =rman_get_bushandle(sc->sc_otg.sc_io_res);sc->sc_otg.sc_io_size =rman_get_size(sc->sc_otg.sc_io_res);sc->sc_otg.sc_bus.bdev = device_add_child(dev, "usbus", -1);if (!(sc->sc_otg.sc_bus.bdev)) {device_printf(dev, "No busdev for musb\n");goto error;}device_set_ivars(sc->sc_otg.sc_bus.bdev,&sc->sc_otg.sc_bus);err = bus_setup_intr(dev, sc->sc_otg.sc_irq_res,INTR_TYPE_BIO | INTR_MPSAFE,NULL, (driver_intr_t *)musbotg_wrapper_interrupt,&sc->sc_otg, &sc->sc_otg.sc_intr_hdl);if (err) {sc->sc_otg.sc_intr_hdl = NULL;device_printf(dev,"Failed to setup interrupt for musb\n");goto error;}sc->sc_otg.sc_platform_data = sc;if (OF_getprop(ofw_bus_get_node(dev), "dr_mode", mode,sizeof(mode)) > 0) {if (strcasecmp(mode, "host") == 0)sc->sc_otg.sc_mode = MUSB2_HOST_MODE;elsesc->sc_otg.sc_mode = MUSB2_DEVICE_MODE;} else {/* Beaglebone defaults: USB0 device, USB1 HOST. */if (sc->sc_otg.sc_id == 0)sc->sc_otg.sc_mode = MUSB2_DEVICE_MODE;elsesc->sc_otg.sc_mode = MUSB2_HOST_MODE;}/** software-controlled function*/if (sc->sc_otg.sc_mode == MUSB2_HOST_MODE) {reg = USBCTRL_READ4(sc, USBCTRL_MODE);reg |= USBCTRL_MODE_IDDIGMUX;reg &= ~USBCTRL_MODE_IDDIG;USBCTRL_WRITE4(sc, USBCTRL_MODE, reg);USBCTRL_WRITE4(sc, USBCTRL_UTMI,USBCTRL_UTMI_FSDATAEXT);} else {reg = USBCTRL_READ4(sc, USBCTRL_MODE);reg |= USBCTRL_MODE_IDDIGMUX;reg |= USBCTRL_MODE_IDDIG;USBCTRL_WRITE4(sc, USBCTRL_MODE, reg);}reg = USBCTRL_INTEN_USB_ALL & ~USBCTRL_INTEN_USB_SOF;USBCTRL_WRITE4(sc, USBCTRL_INTEN_SET1, reg);USBCTRL_WRITE4(sc, USBCTRL_INTEN_CLR0, 0xffffffff);err = musbotg_init(&sc->sc_otg);if (!err)err = device_probe_and_attach(sc->sc_otg.sc_bus.bdev);if (err)goto error;/* poll VBUS one time */musbotg_vbus_poll(sc);return (0);error:musbotg_detach(dev);return (ENXIO);
}static int
musbotg_detach(device_t dev)
{struct musbotg_super_softc *sc = device_get_softc(dev);int err;/* during module unload there are lots of children leftover */device_delete_children(dev);if (sc->sc_otg.sc_irq_res && sc->sc_otg.sc_intr_hdl) {/** only call musbotg_uninit() after musbotg_init()*/musbotg_uninit(&sc->sc_otg);err = bus_teardown_intr(dev, sc->sc_otg.sc_irq_res,sc->sc_otg.sc_intr_hdl);sc->sc_otg.sc_intr_hdl = NULL;}usb_bus_mem_free_all(&sc->sc_otg.sc_bus, NULL);/* Free resources if any */if (sc->sc_mem_res[0])bus_release_resources(dev, am335x_musbotg_mem_spec,sc->sc_mem_res);if (sc->sc_otg.sc_irq_res)bus_release_resource(dev, SYS_RES_IRQ, sc->sc_irq_rid,sc->sc_otg.sc_irq_res);return (0);
}static device_method_t musbotg_methods[] = {/* Device interface */DEVMETHOD(device_probe, musbotg_probe),DEVMETHOD(device_attach, musbotg_attach),DEVMETHOD(device_detach, musbotg_detach),DEVMETHOD(device_suspend, bus_generic_suspend),DEVMETHOD(device_resume, bus_generic_resume),DEVMETHOD(device_shutdown, bus_generic_shutdown),DEVMETHOD_END
};static driver_t musbotg_driver = {.name = "musbotg",.methods = musbotg_methods,.size = sizeof(struct musbotg_super_softc),
};static devclass_t musbotg_devclass;DRIVER_MODULE(musbotg, usbss, musbotg_driver, musbotg_devclass, 0, 0);
MODULE_DEPEND(musbotg, usbss, 1, 1, 1);

首先，musbotg_attach会被usbss文件中的函数所调用，该函数主要实现了对musb的一些配置：

/* Request the memory resources */err = bus_alloc_resources(dev, am335x_musbotg_mem_spec,sc->sc_mem_res);if (err) {device_printf(dev,"Error: could not allocate mem resources\n");return (ENXIO);}/* Request the IRQ resources */sc->sc_otg.sc_irq_res = bus_alloc_resource_any(dev, SYS_RES_IRQ,&sc->sc_irq_rid, RF_ACTIVE);if (sc->sc_otg.sc_irq_res == NULL) {device_printf(dev,"Error: could not allocate irq resources\n");return (ENXIO);}

这一段主要是对musb基础寄存器的资源分配，以及musb的中断资源分配。

/* setup MUSB OTG USB controller interface softc */sc->sc_otg.sc_clocks_on = &musbotg_clocks_on;sc->sc_otg.sc_clocks_off = &musbotg_clocks_off;sc->sc_otg.sc_clocks_arg = &sc->sc_otg;sc->sc_otg.sc_ep_int_set = musbotg_ep_int_set;/* initialise some bus fields */sc->sc_otg.sc_bus.parent = dev;sc->sc_otg.sc_bus.devices = sc->sc_otg.sc_devices;sc->sc_otg.sc_bus.devices_max = MUSB2_MAX_DEVICES;sc->sc_otg.sc_bus.dma_bits = 32;

这一段主要是对一些otg控制接口的配置。

err = bus_setup_intr(dev, sc->sc_otg.sc_irq_res,INTR_TYPE_BIO | INTR_MPSAFE,NULL, (driver_intr_t *)musbotg_wrapper_interrupt,&sc->sc_otg, &sc->sc_otg.sc_intr_hdl);if (err) {sc->sc_otg.sc_intr_hdl = NULL;device_printf(dev,"Failed to setup interrupt for musb\n");goto error;}

接着是设置中断handler，handler名称为：musbotg_wrapper_interrupt。

 sc->sc_otg.sc_platform_data = sc;if (OF_getprop(ofw_bus_get_node(dev), "dr_mode", mode,sizeof(mode)) > 0) {if (strcasecmp(mode, "host") == 0)sc->sc_otg.sc_mode = MUSB2_HOST_MODE;elsesc->sc_otg.sc_mode = MUSB2_DEVICE_MODE;} else {/* Beaglebone defaults: USB0 device, USB1 HOST. */if (sc->sc_otg.sc_id == 0)sc->sc_otg.sc_mode = MUSB2_DEVICE_MODE;elsesc->sc_otg.sc_mode = MUSB2_HOST_MODE;}

然后是对USB模式的匹配和判断。

/*
* software-controlled function
*/if (sc->sc_otg.sc_mode == MUSB2_HOST_MODE) {
reg = USBCTRL_READ4(sc, USBCTRL_MODE);
reg |= USBCTRL_MODE_IDDIGMUX;
reg &= ~USBCTRL_MODE_IDDIG;
USBCTRL_WRITE4(sc, USBCTRL_MODE, reg);
USBCTRL_WRITE4(sc, USBCTRL_UTMI,USBCTRL_UTMI_FSDATAEXT);
} else {
reg = USBCTRL_READ4(sc, USBCTRL_MODE);
reg |= USBCTRL_MODE_IDDIGMUX;
reg |= USBCTRL_MODE_IDDIG;
USBCTRL_WRITE4(sc, USBCTRL_MODE, reg);
}

根据USB主从模式，对musb寄存器进行配置。

 reg = USBCTRL_INTEN_USB_ALL & ~USBCTRL_INTEN_USB_SOF;USBCTRL_WRITE4(sc, USBCTRL_INTEN_SET1, reg);USBCTRL_WRITE4(sc, USBCTRL_INTEN_CLR0, 0xffffffff);err = musbotg_init(&sc->sc_otg);if (!err)err = device_probe_and_attach(sc->sc_otg.sc_bus.bdev);if (err)goto error;/* poll VBUS one time */musbotg_vbus_poll(sc);return (0);error:musbotg_detach(dev);return (ENXIO);

最后清除所有中断，调用musbotg_init函数，该函数在musb_otg.c文件中，该文件主要功能是对otg设备管理进行设置。同样非常重要，该文件位于freebsd/sys/dev/usb/control文件夹下。

static driver_t musbotg_driver = {.name = "musbotg",.methods = musbotg_methods,.size = sizeof(struct musbotg_super_softc),
};static devclass_t musbotg_devclass;DRIVER_MODULE(musbotg, usbss, musbotg_driver, musbotg_devclass, 0, 0);
MODULE_DEPEND(musbotg, usbss, 1, 1, 1);

要注意的是，musb是挂载在usbss下的，因此要注意设备的注册顺序，先注册usbss再注册musb。否则会导致初始化失败。

以上操作基本是RTEMS-libbsd的USB移植的需要的文件和大致步骤。有何疑问或不妥请留言指出。转载请说明出处。

RTEMS-libbsd 实现beaglebone black USB驱动相关推荐

Uboot Beaglebone Black Usb驱动分析
在驱动开发中,USB驱动是比较难以理解的部分,也是令驱动开发者比较头疼的,不仅是因为USB包括host端和设备端:USB的协议类型也非常多:数据传输的协议,控制协议,主控制器协议,设备相关的协议,硬件 ...
2008年12月13日上海USB驱动开发深度解析讲座PPT
讲座PPT:宋宝华2008年12月13日上海USB驱动开发深度解析讲座PPT [url]http://www.linuxdriver.cn/200812/20081213172619_836.rar[ ...
嵌入式Linux USB驱动开发之教你一步步编写USB驱动程序
2019独角兽企业重金招聘Python工程师标准>>> 编写与一个USB设备驱动程序的方法和其他总线驱动方式类似,驱动程序把驱动程序对象注册到USB子系统中,稍后再使用制造商和设备标 ...
MF Porting之USB驱动开发
花费了近三个礼拜的时间,终于完成了TI开发板的USB驱动开发,现在回头想一想,其实也没有什么,具体硬件方面的通信由DM355实现了,软件层面的数据交互由MF Porting实现了,所做的也就是熟悉了解 ...
Linux USB 驱动开发（五）—— USB驱动程序开发过程简单总结
http://blog.csdn.net/zqixiao_09/article/details/51057086 设备驱动程序是操作系统内核和机器硬件之间的接口,由一组函数和一些私有数据组成,是应用程 ...
linux usb驱动
0.usb协议 usb的版本: 硬件 usb 1.0 OHCI 微软硬件 > 软件 usb ...
android 最新usb驱动程序下载,安卓手机USB驱动官方下载、安装教程
如果您想要成功地将安卓手机连接到电脑端进行文件传输.手机ROOT,或者更新手机固件.就不得不需要一个合适的USB驱动.为了方便大家,我们特意收集并整理了比较大众的安卓手机机型USB驱动的下载链接(所有 ...
USB学习5---android usb驱动源代码目录说明
kernel\msm-3.18\drivers\usb下目录内容我们msm8937+android7.1平台编译out目录下usb目录下有编译到的目录如下: 我们先参考kernel\msm-3.18 ...
USB基础---Linux USB驱动层次
在Linux系统中,提供主机侧和设备侧视角的USB驱动框架,从主机侧看到的USB主机控制器和设备驱动,以及从设备侧看到的设备控制器和Gadget驱动. Linux系统中USB驱动的整体视图图1 (1 ...

RTEMS-libbsd 实现beaglebone black USB驱动

RTEMS-libbsd 实现beaglebone black USB驱动相关推荐

最新文章

热门文章