1 files changed, 256 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-viai2c-common.c b/drivers/i2c/busses/i2c-viai2c-common.c
new file mode 100644
index 000000000000..1844d13f1f79
--- /dev/null
+++ b/drivers/i2c/busses/i2c-viai2c-common.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+#include <linux/of_irq.h>
+#include "i2c-viai2c-common.h"
+
+int viai2c_wait_bus_not_busy(struct viai2c *i2c)
+{
+	unsigned long timeout;
+
+	timeout = jiffies + VIAI2C_TIMEOUT;
+	while (!(readw(i2c->base + VIAI2C_REG_CSR) & VIAI2C_CSR_READY_MASK)) {
+		if (time_after(jiffies, timeout)) {
+			dev_warn(i2c->dev, "timeout waiting for bus ready\n");
+			return -EBUSY;
+		}
+		msleep(20);
+	}
+
+	return 0;
+}
+
+static int viai2c_write(struct viai2c *i2c, struct i2c_msg *pmsg, int last)
+{
+	u16 val, tcr_val = i2c->tcr;
+
+	i2c->last = last;
+
+	if (pmsg->len == 0) {
+		/*
+		 * We still need to run through the while (..) once, so
+		 * start at -1 and break out early from the loop
+		 */
+		i2c->xfered_len = -1;
+		writew(0, i2c->base + VIAI2C_REG_CDR);
+	} else {
+		writew(pmsg->buf[0] & 0xFF, i2c->base + VIAI2C_REG_CDR);
+	}
+
+	if (i2c->platform == VIAI2C_PLAT_WMT && !(pmsg->flags & I2C_M_NOSTART)) {
+		val = readw(i2c->base + VIAI2C_REG_CR);
+		val &= ~VIAI2C_CR_TX_END;
+		val |= VIAI2C_CR_CPU_RDY;
+		writew(val, i2c->base + VIAI2C_REG_CR);
+	}
+
+	reinit_completion(&i2c->complete);
+
+	tcr_val |= pmsg->addr & VIAI2C_TCR_ADDR_MASK;
+
+	writew(tcr_val, i2c->base + VIAI2C_REG_TCR);
+
+	if (i2c->platform == VIAI2C_PLAT_WMT && pmsg->flags & I2C_M_NOSTART) {
+		val = readw(i2c->base + VIAI2C_REG_CR);
+		val |= VIAI2C_CR_CPU_RDY;
+		writew(val, i2c->base + VIAI2C_REG_CR);
+	}
+
+	if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT))
+		return -ETIMEDOUT;
+
+	return i2c->ret;
+}
+
+static int viai2c_read(struct viai2c *i2c, struct i2c_msg *pmsg, bool first)
+{
+	u16 val, tcr_val = i2c->tcr;
+
+	val = readw(i2c->base + VIAI2C_REG_CR);
+	val &= ~(VIAI2C_CR_TX_END | VIAI2C_CR_RX_END);
+
+	if (i2c->platform == VIAI2C_PLAT_WMT && !(pmsg->flags & I2C_M_NOSTART))
+		val |= VIAI2C_CR_CPU_RDY;
+
+	if (pmsg->len == 1)
+		val |= VIAI2C_CR_RX_END;
+
+	writew(val, i2c->base + VIAI2C_REG_CR);
+
+	reinit_completion(&i2c->complete);
+
+	tcr_val |= VIAI2C_TCR_READ | (pmsg->addr & VIAI2C_TCR_ADDR_MASK);
+
+	writew(tcr_val, i2c->base + VIAI2C_REG_TCR);
+
+	if ((i2c->platform == VIAI2C_PLAT_WMT && (pmsg->flags & I2C_M_NOSTART)) ||
+	    (i2c->platform == VIAI2C_PLAT_ZHAOXIN && !first)) {
+		val = readw(i2c->base + VIAI2C_REG_CR);
+		val |= VIAI2C_CR_CPU_RDY;
+		writew(val, i2c->base + VIAI2C_REG_CR);
+	}
+
+	if (!wait_for_completion_timeout(&i2c->complete, VIAI2C_TIMEOUT))
+		return -ETIMEDOUT;
+
+	return i2c->ret;
+}
+
+int viai2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+{
+	struct i2c_msg *pmsg;
+	int i;
+	int ret = 0;
+	struct viai2c *i2c = i2c_get_adapdata(adap);
+
+	i2c->mode = VIAI2C_BYTE_MODE;
+	for (i = 0; ret >= 0 && i < num; i++) {
+		pmsg = &msgs[i];
+		if (i2c->platform == VIAI2C_PLAT_WMT && !(pmsg->flags & I2C_M_NOSTART)) {
+			ret = viai2c_wait_bus_not_busy(i2c);
+			if (ret < 0)
+				return ret;
+		}
+
+		i2c->msg = pmsg;
+		i2c->xfered_len = 0;
+
+		if (pmsg->flags & I2C_M_RD)
+			ret = viai2c_read(i2c, pmsg, i == 0);
+		else
+			ret = viai2c_write(i2c, pmsg, (i + 1) == num);
+	}
+
+	return (ret < 0) ? ret : i;
+}
+
+/*
+ * Main process of the byte mode xfer
+ *
+ * Return value indicates whether the transfer is complete
+ *  1: all the data has been successfully transferred
+ *  0: there is still data that needs to be transferred
+ *  -EIO: error occurred
+ */
+static int viai2c_irq_xfer(struct viai2c *i2c)
+{
+	u16 val;
+	struct i2c_msg *msg = i2c->msg;
+	u8 read = msg->flags & I2C_M_RD;
+	void __iomem *base = i2c->base;
+
+	if (read) {
+		msg->buf[i2c->xfered_len] = readw(base + VIAI2C_REG_CDR) >> 8;
+
+		val = readw(base + VIAI2C_REG_CR) | VIAI2C_CR_CPU_RDY;
+		if (i2c->xfered_len == msg->len - 2)
+			val |= VIAI2C_CR_RX_END;
+		writew(val, base + VIAI2C_REG_CR);
+	} else {
+		val = readw(base + VIAI2C_REG_CSR);
+		if (val & VIAI2C_CSR_RCV_NOT_ACK)
+			return -EIO;
+
+		/* I2C_SMBUS_QUICK */
+		if (msg->len == 0) {
+			val = VIAI2C_CR_TX_END | VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE;
+			writew(val, base + VIAI2C_REG_CR);
+			return 1;
+		}
+
+		if ((i2c->xfered_len + 1) == msg->len) {
+			if (i2c->platform == VIAI2C_PLAT_WMT && !i2c->last)
+				writew(VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR);
+			else if (i2c->platform == VIAI2C_PLAT_ZHAOXIN && i2c->last)
+				writeb(VIAI2C_CR_TX_END, base + VIAI2C_REG_CR);
+		} else {
+			writew(msg->buf[i2c->xfered_len + 1] & 0xFF, base + VIAI2C_REG_CDR);
+			writew(VIAI2C_CR_CPU_RDY | VIAI2C_CR_ENABLE, base + VIAI2C_REG_CR);
+		}
+	}
+
+	i2c->xfered_len++;
+
+	return i2c->xfered_len == msg->len;
+}
+
+int __weak viai2c_fifo_irq_xfer(struct viai2c *i2c, bool irq)
+{
+	return 0;
+}
+
+static irqreturn_t viai2c_isr(int irq, void *data)
+{
+	struct viai2c *i2c = data;
+	u8 status;
+
+	/* save the status and write-clear it */
+	status = readw(i2c->base + VIAI2C_REG_ISR);
+	if (!status && i2c->platform == VIAI2C_PLAT_ZHAOXIN)
+		return IRQ_NONE;
+
+	writew(status, i2c->base + VIAI2C_REG_ISR);
+
+	i2c->ret = 0;
+	if (status & VIAI2C_ISR_NACK_ADDR)
+		i2c->ret = -EIO;
+
+	if (i2c->platform == VIAI2C_PLAT_WMT && (status & VIAI2C_ISR_SCL_TIMEOUT))
+		i2c->ret = -ETIMEDOUT;
+
+	if (!i2c->ret) {
+		if (i2c->mode == VIAI2C_BYTE_MODE)
+			i2c->ret = viai2c_irq_xfer(i2c);
+		else
+			i2c->ret = viai2c_fifo_irq_xfer(i2c, true);
+	}
+
+	/* All the data has been successfully transferred or error occurred */
+	if (i2c->ret)
+		complete(&i2c->complete);
+
+	return IRQ_HANDLED;
+}
+
+int viai2c_init(struct platform_device *pdev, struct viai2c **pi2c, int plat)
+{
+	int err;
+	int irq_flags;
+	struct viai2c *i2c;
+	struct device_node *np = pdev->dev.of_node;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
+	if (!i2c)
+		return -ENOMEM;
+
+	i2c->base = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
+	if (IS_ERR(i2c->base))
+		return PTR_ERR(i2c->base);
+
+	if (plat == VIAI2C_PLAT_WMT) {
+		irq_flags = 0;
+		i2c->irq = irq_of_parse_and_map(np, 0);
+		if (!i2c->irq)
+			return -EINVAL;
+	} else if (plat == VIAI2C_PLAT_ZHAOXIN) {
+		irq_flags = IRQF_SHARED;
+		i2c->irq = platform_get_irq(pdev, 0);
+		if (i2c->irq < 0)
+			return i2c->irq;
+	} else {
+		return dev_err_probe(&pdev->dev, -EINVAL, "wrong platform type\n");
+	}
+
+	i2c->platform = plat;
+
+	err = devm_request_irq(&pdev->dev, i2c->irq, viai2c_isr,
+			       irq_flags, pdev->name, i2c);
+	if (err)
+		return dev_err_probe(&pdev->dev, err,
+				"failed to request irq %i\n", i2c->irq);
+
+	i2c->dev = &pdev->dev;
+	init_completion(&i2c->complete);
+	platform_set_drvdata(pdev, i2c);
+
+	*pi2c = i2c;
+	return 0;
+}