On 24/01/2017 08:05, zhichang.yuan wrote:

It's not a workaround, it's support. Better word it like

   "Support for ISA I/O space on Hisilicon HIP0X"

legacy?

I don't really understand why this bus is legacy though. It looks like a 
simple MMIO-to-LPC bridge to me.

+ * The port size of legacy I/O devices is normally less than 0x400.
+ * Defining the I/O range size as 0x400 here should be sufficient for
+ * all peripherals under one bus.
+ */

This comment doesn't make a lot of sense. What is the limit? Is there a 
hardware limit?

We don't dynamically allocate devices on the lpc bus, so why imply a 
limit at all?

+#define LPC_BUS_IO_SIZE		0x400
+
+/* The maximum continuous operations */
+#define LPC_MAX_OPCNT	16
+/* only support IO data unit length is four at maximum */
+#define LPC_MAX_DULEN	4
+#if LPC_MAX_DULEN > LPC_MAX_OPCNT
+#error "LPC.. MAX_DULEN must be not bigger than MAX_OPCNT!"
+#endif
+
+#define LPC_REG_START		0x00 /* start a new LPC cycle */
+#define LPC_REG_OP_STATUS	0x04 /* the current LPC status */
+#define LPC_REG_IRQ_ST		0x08 /* interrupt enable&status */
+#define LPC_REG_OP_LEN		0x10 /* how many LPC cycles each start */
+#define LPC_REG_CMD		0x14 /* command for the required LPC cycle */
+#define LPC_REG_ADDR		0x20 /* LPC target address */
+#define LPC_REG_WDATA		0x24 /* data to be written */
+#define LPC_REG_RDATA		0x28 /* data coming from peer */
+
+
+/* The command register fields */
+#define LPC_CMD_SAMEADDR	0x08
+#define LPC_CMD_TYPE_IO		0x00
+#define LPC_CMD_WRITE		0x01
+#define LPC_CMD_READ		0x00
+/* the bit attribute is W1C. 1 represents OK. */
+#define LPC_STAT_BYIRQ		0x02
+
+#define LPC_STATUS_IDLE		0x01
+#define LPC_OP_FINISHED		0x02
+
+#define START_WORK		0x01
+
+/*
+ * The minimal waiting interval... Suggest it is not less than 10.
+ * Bigger value probably will lower the performance.

Are you sure you want this comment to be upstream? :)

+ */
+#define LPC_NSEC_PERWAIT	100
+/*
+ * The maximum waiting time is about 128us.
+ * The fastest IO cycle time is about 390ns, but the worst case will wait
+ * for extra 256 lpc clocks, so (256 + 13) * 30ns = 8 us. The maximum
+ * burst cycles is 16. So, the maximum waiting time is about 128us under
+ * worst case.
+ * choose 1300 as the maximum.
+ */
+#define LPC_MAX_WAITCNT		1300
+/* About 10us. This is specific for single IO operation, such as inb. */
+#define LPC_PEROP_WAITCNT	100
+
+
+static inline int wait_lpc_idle(unsigned char *mbase,

No need to specify inline.

+				unsigned int waitcnt) {
+	u32 opstatus;
+
+	while (waitcnt--) {
+		ndelay(LPC_NSEC_PERWAIT);
+		opstatus = readl(mbase + LPC_REG_OP_STATUS);
+		if (opstatus & LPC_STATUS_IDLE)
+			return (opstatus & LPC_OP_FINISHED) ? 0 : (-EIO);

It's a shame we have to busy loop, but I guess no calling code outside 
is prepared for rescheduling at this point.

+	}
+	return -ETIME;
+}
+
+/*
+ * hisilpc_target_in - trigger a series of lpc cycles to read required data
+ *		       from target peripheral.
+ * @pdev: pointer to hisi lpc device
+ * @para: some parameters used to control the lpc I/O operations
+ * @ptaddr: the lpc I/O target port address
+ * @buf: where the read back data is stored
+ * @opcnt: how many I/O operations required in this calling
+ *
+ * Only one byte data is read each I/O operation.
+ *
+ * Returns 0 on success, non-zero on fail.
+ *
+ */
+static int
+hisilpc_target_in(struct hisilpc_dev *lpcdev, struct lpc_cycle_para *para,
+		  unsigned long ptaddr, unsigned char *buf,
+		  unsigned long opcnt)
+{
+	unsigned long cnt_per_trans;
+	unsigned int cmd_word;
+	unsigned int waitcnt;
+	int ret;
+
+	if (!buf || !opcnt || !para || !para->csize || !lpcdev)
+		return -EINVAL;
+
+	if (opcnt  > LPC_MAX_OPCNT)
+		return -EINVAL;
+
+	cmd_word = LPC_CMD_TYPE_IO | LPC_CMD_READ;
+	waitcnt = LPC_PEROP_WAITCNT;
+	if (!(para->opflags & FG_INCRADDR_LPC)) {
+		cmd_word |= LPC_CMD_SAMEADDR;
+		waitcnt = LPC_MAX_WAITCNT;
+	}
+
+	ret = 0;
+	cnt_per_trans = (para->csize == 1) ? opcnt : para->csize;
+	for (; opcnt && !ret; cnt_per_trans = para->csize) {
+		unsigned long flags;
+
+		/* whole operation must be atomic */
+		spin_lock_irqsave(&lpcdev->cycle_lock, flags);

Ouch. This is going to kill your RT jitter. Is there no better way?

+
+		writel(cnt_per_trans, lpcdev->membase + LPC_REG_OP_LEN);
+
+		writel(cmd_word, lpcdev->membase + LPC_REG_CMD);
+
+		writel(ptaddr, lpcdev->membase + LPC_REG_ADDR);
+
+		writel(START_WORK, lpcdev->membase + LPC_REG_START);
+
+		/* whether the operation is finished */
+		ret = wait_lpc_idle(lpcdev->membase, waitcnt);
+		if (!ret) {
+			opcnt -= cnt_per_trans;
+			for (; cnt_per_trans--; buf++)
+				*buf = readl(lpcdev->membase + LPC_REG_RDATA);
+		}
+
+		spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
+	}
+
+	return ret;
+}
+
+/**
+ * hisilpc_target_out - trigger a series of lpc cycles to write required
+ *			data to target peripheral.
+ * @pdev: pointer to hisi lpc device
+ * @para: some parameters used to control the lpc I/O operations
+ * @ptaddr: the lpc I/O target port address
+ * @buf: where the data to be written is stored
+ * @opcnt: how many I/O operations required
+ *
+ * Only one byte data is read each I/O operation.
+ *
+ * Returns 0 on success, non-zero on fail.
+ *
+ */
+static int
+hisilpc_target_out(struct hisilpc_dev *lpcdev, struct lpc_cycle_para *para,
+		   unsigned long ptaddr, const unsigned char *buf,
+		   unsigned long opcnt)
+{
+	unsigned long cnt_per_trans;
+	unsigned int cmd_word;
+	unsigned int waitcnt;
+	int ret;
+
+	if (!buf || !opcnt || !para || !lpcdev)
+		return -EINVAL;
+
+	if (opcnt > LPC_MAX_OPCNT)
+		return -EINVAL;
+	/* default is increasing address */
+	cmd_word = LPC_CMD_TYPE_IO | LPC_CMD_WRITE;
+	waitcnt = LPC_PEROP_WAITCNT;
+	if (!(para->opflags & FG_INCRADDR_LPC)) {
+		cmd_word |= LPC_CMD_SAMEADDR;
+		waitcnt = LPC_MAX_WAITCNT;
+	}
+
+	ret = 0;
+	cnt_per_trans = (para->csize == 1) ? opcnt : para->csize;
+	for (; opcnt && !ret; cnt_per_trans = para->csize) {
+		unsigned long flags;
+
+		spin_lock_irqsave(&lpcdev->cycle_lock, flags);

Same thing here

+
+		writel(cnt_per_trans, lpcdev->membase + LPC_REG_OP_LEN);
+		opcnt -= cnt_per_trans;
+		for (; cnt_per_trans--; buf++)
+			writel(*buf, lpcdev->membase + LPC_REG_WDATA);
+
+		writel(cmd_word, lpcdev->membase + LPC_REG_CMD);
+
+		writel(ptaddr, lpcdev->membase + LPC_REG_ADDR);
+
+		writel(START_WORK, lpcdev->membase + LPC_REG_START);
+
+		/* whether the operation is finished */
+		ret = wait_lpc_idle(lpcdev->membase, waitcnt);
+
+		spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
+	}
+
+	return ret;
+}
+
+static inline unsigned long

Don't explicitly mention inline, the compiler will figure that out for you.

+hisi_lpc_pio_to_addr(struct hisilpc_dev *lpcdev, unsigned long pio)
+{
+	return pio - lpcdev->extio->io_start + lpcdev->extio->bus_start;
+}
+
+
+/**
+ * hisilpc_comm_in - read/input the data from the I/O peripheral
+ *		     through LPC.
+ * @devobj: pointer to the device information relevant to LPC controller.
+ * @pio: the target I/O port address.
+ * @dlen: the data length required to read from the target I/O port.
+ *
+ * when succeed, the data read back is stored in buffer pointed by inbuf.
+ * For inb, return the data read from I/O or -1 when error occur.
+ */
+static u64 hisilpc_comm_in(void *devobj, unsigned long pio, size_t dlen)
+{
+	struct hisilpc_dev *lpcdev = devobj;
+	struct lpc_cycle_para iopara;
+	u32 rd_data;

rd_data needs to be initialized to 0. Otherwise it may contain stale 
stack contents and corrupt non-32bit dlen returns.

+	unsigned char *newbuf;
+	int ret = 0;
+	unsigned long ptaddr;
+
+	if (!lpcdev || !dlen || dlen > LPC_MAX_DULEN ||	(dlen & (dlen - 1)))
+		return -1;

Isn't this -EINVAL?

+
+	/* the local buffer must be enough for one data unit */
+	if (sizeof(rd_data) < dlen)
+		return -1;

Same here.

Also, the above seems a very convoluted way of saying

   switch (dlen) {
   case 1:
   case 2:
   case 4:
     break;
   default:
     return -EINVAL;
   }

But I guess the way you write it doesn't hurt ;)


Alex