Hi Andy,
On 07/07/2017 11:25 AM, Andy Shevchenko wrote:
On Mon, Jun 19, 2017 at 11:36 PM, <thor.thayer@xxxxxxxxxxxxxxx> wrote:
Either...
+#include <linux/init.h>
...or...
+#include <linux/module.h>
...choose one.
+#define ALTR_I2C_THRESHOLD 0 /*IRQ Threshold at 1 element */
Space missed.
Got it. Thanks!
+/**
+ * altr_i2c_empty_rx_fifo - Fetch data from RX FIFO until end of
+ * transfer. Send a Stop bit on the last byte.
+ */
+static void altr_i2c_empty_rx_fifo(struct altr_i2c_dev *idev)
+{
+ size_t rx_fifo_avail = readl(idev->base + ALTR_I2C_RX_FIFO_LVL);
+ int bytes_to_transfer = min(rx_fifo_avail, idev->msg_len);
+
+ while (bytes_to_transfer-- > 0) {
+ *idev->buf++ = readl(idev->base + ALTR_I2C_RX_DATA);
+ if (idev->msg_len == 1)
+ altr_i2c_stop(idev);
+ else
+ writel(0, idev->base + ALTR_I2C_TFR_CMD);
+
+ idev->msg_len--;
+ }
Move out invariant from the loop (and I see a bug, you might go over
boundaries).
while (bytes_to_transfer-- > 0) {
*idev->buf++ = readl(idev->base + ALTR_I2C_RX_DATA);
if (idev->msg_len-- == 1)
break;
writel(0, idev->base + ALTR_I2C_TFR_CMD);
}
altr_i2c_stop(idev);
I see your point on the boundary. However your change is slightly
different from what I'm trying to do.
I think you assumed the alt_i2c_stop() call can cause a stop condition.
This soft IP can't send just a start or a stop condition by itself -
both of these conditions need to be paired with a byte.
The other subtle side effect is the start condition + byte write is the
first write which is why the last write is skipped.
I need to send a byte with a stop condition on the last expected byte
(idev->msg_len == 1) while this change would send it after the FIFO is
empty or after (msg_len == 1).
Your version is cleaner so I'll just add the alt_i2c_stop(idev) call
inside the (msg_len == 1) condition and before the break.
+}
+
+/**
+ * altr_i2c_fill_tx_fifo - Fill TX FIFO from current message buffer.
+ * @return: Number of bytes left to transfer.
+ */
+static int altr_i2c_fill_tx_fifo(struct altr_i2c_dev *idev)
+{
+ size_t tx_fifo_avail = idev->fifo_size - readl(idev->base +
+ ALTR_I2C_TC_FIFO_LVL);
+ int bytes_to_transfer = min(tx_fifo_avail, idev->msg_len);
+ int ret = idev->msg_len - bytes_to_transfer;
+
+ while (bytes_to_transfer-- > 0) {
+ if (idev->msg_len == 1)
+ writel(ALTR_I2C_TFR_CMD_STO | *idev->buf++,
+ idev->base + ALTR_I2C_TFR_CMD);
+ else
+ writel(*idev->buf++, idev->base + ALTR_I2C_TFR_CMD);
+ idev->msg_len--;
+ }
Ditto.
See above but I will move the msg_len-- inside the condition check like
you had.
+
+ return ret;
+}
+/**
+ * altr_i2c_wait_for_core_idle - After TX, check core idle for all bytes TX.
+ * @return: 0 on success or -ETIMEDOUT on timeout.
+ */
+static int altr_i2c_wait_for_core_idle(struct altr_i2c_dev *idev)
+{
+ unsigned long timeout = jiffies + msecs_to_jiffies(ALTR_I2C_TIMEOUT);
+
+ do {
+ if (time_after(jiffies, timeout)) {
+ dev_err(idev->dev, "Core Idle timeout\n");
+ return -ETIMEDOUT;
+ }
+ } while (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE);
+
+ return 0;
+}
readl_poll_timeout[_atomic]() please.
+static irqreturn_t altr_i2c_isr(int irq, void *_dev)
+{
+ struct altr_i2c_dev *idev = _dev;
+ /* Read IRQ status but only interested in Enabled IRQs. */
+ u32 status = readl(idev->base + ALTR_I2C_ISR) &
+ readl(idev->base + ALTR_I2C_ISER);
Don't you have cached value for mask?
Not right now, but it may be good to add that to the altr_i2c_dev structure.
+}
+
+static int altr_i2c_xfer_msg(struct altr_i2c_dev *idev, struct i2c_msg *msg)
+{
+ u32 int_mask = ALTR_I2C_ISR_RXOF | ALTR_I2C_ISR_ARB | ALTR_I2C_ISR_NACK;
+ u32 addr = (msg->addr << 1) & 0xFF;
i2c_8bit_addr_from_msg() ?
Nice! I missed that function when writing this but I like it since it
also simplifies the code below.
+ unsigned long time_left;
+
+ if (i2c_m_rd(msg)) {
+ /* Dummy read to ensure RX FIFO is empty */
+ readl(idev->base + ALTR_I2C_RX_DATA);
+ addr |= ALTR_I2C_TFR_CMD_RW_D;
+ }
+
+ writel(ALTR_I2C_TFR_CMD_STA | addr, idev->base + ALTR_I2C_TFR_CMD);
+
+ if (i2c_m_rd(msg)) {
+ /* write the first byte to start the RX */
+ writel(0, idev->base + ALTR_I2C_TFR_CMD);
+ int_mask |= ALTR_I2C_ISER_RXOF_EN | ALTR_I2C_ISER_RXRDY_EN;
+ } else {
+ altr_i2c_fill_tx_fifo(idev);
+ int_mask |= ALTR_I2C_ISR_TXRDY;
+ }
It's hard to follow. Perhaps
if (read) {
...do for read...
} else {
...do for write...
}
Will do. This will be much cleaner, especially with the
i2c_8bit_addr_from_msg() function you pointed out. Thanks!
+ if (readl(idev->base + ALTR_I2C_STATUS) & ALTR_I2C_STAT_CORE)
+ dev_err(idev->dev, "%s: Core Status not IDLE...\n", __func__);
Better to
val = readl();
if (val)
...
Got it. Thanks!
+static int
+altr_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
Why [] ?!
+ struct altr_i2c_dev *idev = i2c_get_adapdata(adap);
+ int i;
+ int ret = 0;
+
+ for (i = 0; ret == 0 && i < num; ++i)
+ ret = altr_i2c_xfer_msg(idev, &msgs[i]);
+
+ return ret ? : i;
Oy vey...
Perhaps
static int altr_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg
*msgs, int num)
{
struct altr_i2c_dev *idev = i2c_get_adapdata(adap);
int ret;
while (num--) {
ret = altr_i2c_xfer_msg(idev, msgs++);
if (ret)
return ret;
}
return 0;
}
Yes, I just copied this from the axxia driver but I'll clean this up for
my re-write.
+static u32 altr_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C;
+}
Useless. Use value in place.
Got it. Thanks!
+static int altr_i2c_probe(struct platform_device *pdev)
+{
+ struct device_node *np = pdev->dev.of_node;
+ struct altr_i2c_dev *idev = NULL;
+ struct resource *res;
+ int irq;
+ int ret = 0;
Redundant assignment.
+ if (of_property_read_u32(np, "fifo-size", &idev->fifo_size))
+ idev->fifo_size = ALTR_I2C_DFLT_FIFO_SZ;
Shouldn't be possible to auto detect?
I agree. That would have been SO much better but the hardware designers
released this without capturing the size in a register - they come from
a bare-metal project perspective. Since the FIFO size is configurable
in the FPGA from 4 to 256 levels deep, I need to capture this with the
device tree.
+ if (of_property_read_u32(np, "clock-frequency", &idev->bus_clk_rate)) {
device_property_*() ?
OK. This is another function I wasn't aware of but I see the
i2c-designware-platdrv.c uses it too.
IIUC, it seems like this falls back to the device tree if the device
properties aren't defined.
+ dev_err(&pdev->dev, "Default to 100kHz\n");
+ idev->bus_clk_rate = 100000; /* default clock rate */
+ }
Great comments! Thanks for reviewing!
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