Slightly improve and generify the USB infrastructure.

The good news is that <libmaple/usb.h> and <libmaple/usb_cdcacm.h> did
turn out generic enough in what they specify to go on unchanged.

However, we can't just go on assuming that there's USB just because
we're on an F1. Now that there's value line in the tree, we need to be
more careful (value line F1s don't have USB peripherals). To that end,
make all the F1 board-includes/*.mk files specify what line their MCU
is with an MCU_F1_LINE variable. Use that to hack
libmaple/usb/rules.mk so we only try to build the USB module under
appropriate circumstances.

While we're at it, add a vector_symbols.inc for value line MCUs under
support/ld/. We need this to get the target-config.mk modifications
implied by the addition of MCU_F1_LINE. We'll fix up some other
performance-line-isms under libmaple/stm32f1 in a separate commit.

Also in libmaple/usb/:

- Move everything into a new stm32f1 directory. Due to aforementioned
  rules.mk hacks, there is no immediate need for an stm32f2
  directory (USB support doesn't exist there).

- Update the README for style and content.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

1 files changed, 381 insertions, 0 deletions

diff --git a/libmaple/usb/stm32f1/usb.c b/libmaple/usb/stm32f1/usb.c
new file mode 100644
index 0000000..0130bab
--- /dev/null
+++ b/libmaple/usb/stm32f1/usb.c
@@ -0,0 +1,381 @@
+/******************************************************************************
+ * The MIT License
+ *
+ * Copyright (c) 2010 LeafLabs LLC.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *****************************************************************************/
+
+/**
+ * @file libmaple/usb/usb.c
+ * @brief USB support.
+ *
+ * This is a mess. What we need almost amounts to a ground-up rewrite.
+ */
+
+#include <libmaple/usb.h>
+
+#include <libmaple/libmaple.h>
+#include <libmaple/rcc.h>
+
+/* Private headers */
+#include "usb_reg_map.h"
+#include "usb_lib_globals.h"
+
+/* usb_lib headers */
+#include "usb_type.h"
+#include "usb_core.h"
+
+static void dispatch_ctr_lp(void);
+
+/*
+ * usb_lib/ globals
+ */
+
+uint16 SaveTState;              /* caches TX status for later use */
+uint16 SaveRState;              /* caches RX status for later use */
+
+/*
+ * Other state
+ */
+
+typedef enum {
+    RESUME_EXTERNAL,
+    RESUME_INTERNAL,
+    RESUME_LATER,
+    RESUME_WAIT,
+    RESUME_START,
+    RESUME_ON,
+    RESUME_OFF,
+    RESUME_ESOF
+} RESUME_STATE;
+
+struct {
+  volatile RESUME_STATE eState;
+  volatile uint8 bESOFcnt;
+} ResumeS;
+
+static usblib_dev usblib = {
+    .irq_mask = USB_ISR_MSK,
+    .state = USB_UNCONNECTED,
+    .clk_id = RCC_USB,
+};
+usblib_dev *USBLIB = &usblib;
+
+/*
+ * Routines
+ */
+
+void usb_init_usblib(usblib_dev *dev,
+                     void (**ep_int_in)(void),
+                     void (**ep_int_out)(void)) {
+    rcc_clk_enable(dev->clk_id);
+
+    dev->ep_int_in = ep_int_in;
+    dev->ep_int_out = ep_int_out;
+
+    /* usb_lib/ declares both and then assumes that pFoo points to Foo
+     * (even though the names don't always match), which is stupid for
+     * all of the obvious reasons, but whatever.  Here we are. */
+    pInformation = &Device_Info;
+    pProperty = &Device_Property;
+    pUser_Standard_Requests = &User_Standard_Requests;
+
+    pInformation->ControlState = 2; /* FIXME [0.0.12] use
+                                       CONTROL_STATE enumerator */
+    pProperty->Init();
+}
+
+static void usb_suspend(void) {
+  uint16 cntr;
+
+  /* TODO decide if read/modify/write is really what we want
+   * (e.g. usb_resume_init() reconfigures CNTR). */
+  cntr = USB_BASE->CNTR;
+  cntr |= USB_CNTR_FSUSP;
+  USB_BASE->CNTR = cntr;
+  cntr |= USB_CNTR_LP_MODE;
+  USB_BASE->CNTR = cntr;
+
+  USBLIB->state = USB_SUSPENDED;
+}
+
+static void usb_resume_init(void) {
+  uint16 cntr;
+
+  cntr = USB_BASE->CNTR;
+  cntr &= ~USB_CNTR_LP_MODE;
+  USB_BASE->CNTR = cntr;
+
+  /* Enable interrupt lines */
+  USB_BASE->CNTR = USB_ISR_MSK;
+}
+
+static void usb_resume(RESUME_STATE eResumeSetVal) {
+  uint16 cntr;
+
+  if (eResumeSetVal != RESUME_ESOF)
+    ResumeS.eState = eResumeSetVal;
+
+  switch (ResumeS.eState)
+    {
+    case RESUME_EXTERNAL:
+      usb_resume_init();
+      ResumeS.eState = RESUME_OFF;
+      break;
+    case RESUME_INTERNAL:
+      usb_resume_init();
+      ResumeS.eState = RESUME_START;
+      break;
+    case RESUME_LATER:
+      ResumeS.bESOFcnt = 2;
+      ResumeS.eState = RESUME_WAIT;
+      break;
+    case RESUME_WAIT:
+      ResumeS.bESOFcnt--;
+      if (ResumeS.bESOFcnt == 0)
+        ResumeS.eState = RESUME_START;
+      break;
+    case RESUME_START:
+      cntr = USB_BASE->CNTR;
+      cntr |= USB_CNTR_RESUME;
+      USB_BASE->CNTR = cntr;
+      ResumeS.eState = RESUME_ON;
+      ResumeS.bESOFcnt = 10;
+      break;
+    case RESUME_ON:
+      ResumeS.bESOFcnt--;
+      if (ResumeS.bESOFcnt == 0) {
+          cntr = USB_BASE->CNTR;
+          cntr &= ~USB_CNTR_RESUME;
+          USB_BASE->CNTR = cntr;
+          ResumeS.eState = RESUME_OFF;
+      }
+      break;
+    case RESUME_OFF:
+    case RESUME_ESOF:
+    default:
+      ResumeS.eState = RESUME_OFF;
+      break;
+    }
+}
+
+#define SUSPEND_ENABLED 1
+void __irq_usb_lp_can_rx0(void) {
+  uint16 istr = USB_BASE->ISTR;
+
+  /* Use USB_ISR_MSK to only include code for bits we care about. */
+
+#if (USB_ISR_MSK & USB_ISTR_RESET)
+  if (istr & USB_ISTR_RESET & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_RESET;
+    pProperty->Reset();
+  }
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_PMAOVR)
+  if (istr & ISTR_PMAOVR & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_PMAOVR;
+  }
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_ERR)
+  if (istr & USB_ISTR_ERR & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_ERR;
+  }
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_WKUP)
+  if (istr & USB_ISTR_WKUP & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_WKUP;
+    usb_resume(RESUME_EXTERNAL);
+  }
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_SUSP)
+  if (istr & USB_ISTR_SUSP & USBLIB->irq_mask) {
+    /* check if SUSPEND is possible */
+    if (SUSPEND_ENABLED) {
+        usb_suspend();
+    } else {
+        /* if not possible then resume after xx ms */
+        usb_resume(RESUME_LATER);
+    }
+    /* clear of the ISTR bit must be done after setting of CNTR_FSUSP */
+    USB_BASE->ISTR = ~USB_ISTR_SUSP;
+}
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_SOF)
+  if (istr & USB_ISTR_SOF & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_SOF;
+  }
+#endif
+
+#if (USB_ISR_MSK & USB_ISTR_ESOF)
+  if (istr & USB_ISTR_ESOF & USBLIB->irq_mask) {
+    USB_BASE->ISTR = ~USB_ISTR_ESOF;
+    /* resume handling timing is made with ESOFs */
+    usb_resume(RESUME_ESOF); /* request without change of the machine state */
+  }
+#endif
+
+  /*
+   * Service the correct transfer interrupt.
+   */
+
+#if (USB_ISR_MSK & USB_ISTR_CTR)
+  if (istr & USB_ISTR_CTR & USBLIB->irq_mask) {
+    dispatch_ctr_lp();
+  }
+#endif
+}
+
+/*
+ * Auxiliary routines
+ */
+
+static inline uint8 dispatch_endpt_zero(uint16 istr_dir);
+static inline void dispatch_endpt(uint8 ep);
+static inline void set_rx_tx_status0(uint16 rx, uint16 tx);
+
+static void handle_setup0(void);
+static void handle_in0(void);
+static void handle_out0(void);
+
+static void dispatch_ctr_lp() {
+    uint16 istr;
+    while (((istr = USB_BASE->ISTR) & USB_ISTR_CTR) != 0) {
+        /* TODO WTF, figure this out: RM0008 says CTR is read-only,
+         * but ST's firmware claims it's clear-only, and emphasizes
+         * the importance of clearing it in more than one place. */
+        USB_BASE->ISTR = ~USB_ISTR_CTR;
+        uint8 ep_id = istr & USB_ISTR_EP_ID;
+        if (ep_id == 0) {
+            /* TODO figure out why it's OK to break out of the loop
+             * once we're done serving endpoint zero, but not okay if
+             * there are multiple nonzero endpoint transfers to
+             * handle. */
+            if (dispatch_endpt_zero(istr & USB_ISTR_DIR))
+                return;
+        } else {
+            dispatch_endpt(ep_id);
+        }
+    }
+}
+
+/* FIXME Dataflow on endpoint 0 RX/TX status is based off of ST's
+ * code, and is ugly/confusing in its use of SaveRState/SaveTState.
+ * Fixing this requires filling in handle_in0(), handle_setup0(),
+ * handle_out0(). */
+static inline uint8 dispatch_endpt_zero(uint16 istr_dir) {
+    uint32 epr = (uint16)USB_BASE->EP[0];
+
+    if (!(epr & (USB_EP_CTR_TX | USB_EP_SETUP | USB_EP_CTR_RX))) {
+        return 0;
+    }
+
+    /* Cache RX/TX statuses in SaveRState/SaveTState, respectively.
+     * The various handle_foo0() may clobber these values
+     * before we reset them at the end of this routine. */
+    SaveRState = epr & USB_EP_STAT_RX;
+    SaveTState = epr & USB_EP_STAT_TX;
+
+    /* Set actual RX/TX statuses to NAK while we're thinking */
+    set_rx_tx_status0(USB_EP_STAT_RX_NAK, USB_EP_STAT_TX_NAK);
+
+    if (istr_dir == 0) {
+        /* ST RM0008: "If DIR bit=0, CTR_TX bit is set in the USB_EPnR
+         * register related to the interrupting endpoint.  The
+         * interrupting transaction is of IN type (data transmitted by
+         * the USB peripheral to the host PC)." */
+        ASSERT_FAULT(epr & USB_EP_CTR_TX);
+        usb_clear_ctr_tx(USB_EP0);
+        handle_in0();
+    } else {
+        /* RM0008: "If DIR bit=1, CTR_RX bit or both CTR_TX/CTR_RX
+         * are set in the USB_EPnR register related to the
+         * interrupting endpoint. The interrupting transaction is of
+         * OUT type (data received by the USB peripheral from the host
+         * PC) or two pending transactions are waiting to be
+         * processed."
+         *
+         * [mbolivar] Note how the following control flow (which
+         * replicates ST's) doesn't seem to actually handle both
+         * interrupts that are ostensibly pending when both CTR_RX and
+         * CTR_TX are set.
+         *
+         * TODO sort this mess out.
+         */
+        if (epr & USB_EP_CTR_TX) {
+            usb_clear_ctr_tx(USB_EP0);
+            handle_in0();
+        } else {                /* SETUP or CTR_RX */
+            /* SETUP is held constant while CTR_RX is set, so clear it
+             * either way */
+            usb_clear_ctr_rx(USB_EP0);
+            if (epr & USB_EP_SETUP) {
+                handle_setup0();
+            } else {            /* CTR_RX */
+                handle_out0();
+            }
+        }
+    }
+
+    set_rx_tx_status0(SaveRState, SaveTState);
+    return 1;
+}
+
+static inline void dispatch_endpt(uint8 ep) {
+    uint32 epr = USB_BASE->EP[ep];
+    /* If ISTR_CTR is set and the ISTR gave us this EP_ID to handle,
+     * then presumably at least one of CTR_RX and CTR_TX is set, but
+     * again, ST's control flow allows for the possibility of neither.
+     *
+     * TODO try to find out if neither being set is possible. */
+    if (epr & USB_EP_CTR_RX) {
+        usb_clear_ctr_rx(ep);
+        (USBLIB->ep_int_out[ep - 1])();
+    }
+    if (epr & USB_EP_CTR_TX) {
+        usb_clear_ctr_tx(ep);
+        (USBLIB->ep_int_in[ep - 1])();
+    }
+}
+
+static inline void set_rx_tx_status0(uint16 rx, uint16 tx) {
+    usb_set_ep_rx_stat(USB_EP0, rx);
+    usb_set_ep_tx_stat(USB_EP0, tx);
+}
+
+/* TODO Rip out usb_lib/ dependency from the following functions: */
+
+static void handle_setup0(void) {
+    Setup0_Process();
+}
+
+static void handle_in0(void) {
+    In0_Process();
+}
+
+static void handle_out0(void) {
+    Out0_Process();
+}