--- /dev/null
+/*
+ * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define UNIPHIER_I2C_DTRM 0x00 /* TX register */
+#define UNIPHIER_I2C_DTRM_IRQEN BIT(11) /* enable interrupt */
+#define UNIPHIER_I2C_DTRM_STA BIT(10) /* start condition */
+#define UNIPHIER_I2C_DTRM_STO BIT(9) /* stop condition */
+#define UNIPHIER_I2C_DTRM_NACK BIT(8) /* do not return ACK */
+#define UNIPHIER_I2C_DTRM_RD BIT(0) /* read transaction */
+#define UNIPHIER_I2C_DREC 0x04 /* RX register */
+#define UNIPHIER_I2C_DREC_MST BIT(14) /* 1 = master, 0 = slave */
+#define UNIPHIER_I2C_DREC_TX BIT(13) /* 1 = transmit, 0 = receive */
+#define UNIPHIER_I2C_DREC_STS BIT(12) /* stop condition detected */
+#define UNIPHIER_I2C_DREC_LRB BIT(11) /* no ACK */
+#define UNIPHIER_I2C_DREC_LAB BIT(9) /* arbitration lost */
+#define UNIPHIER_I2C_DREC_BBN BIT(8) /* bus not busy */
+#define UNIPHIER_I2C_MYAD 0x08 /* slave address */
+#define UNIPHIER_I2C_CLK 0x0c /* clock frequency control */
+#define UNIPHIER_I2C_BRST 0x10 /* bus reset */
+#define UNIPHIER_I2C_BRST_FOEN BIT(1) /* normal operation */
+#define UNIPHIER_I2C_BRST_RSCL BIT(0) /* release SCL */
+#define UNIPHIER_I2C_HOLD 0x14 /* hold time control */
+#define UNIPHIER_I2C_BSTS 0x18 /* bus status monitor */
+#define UNIPHIER_I2C_BSTS_SDA BIT(1) /* readback of SDA line */
+#define UNIPHIER_I2C_BSTS_SCL BIT(0) /* readback of SCL line */
+#define UNIPHIER_I2C_NOISE 0x1c /* noise filter control */
+#define UNIPHIER_I2C_SETUP 0x20 /* setup time control */
+
+#define UNIPHIER_I2C_DEFAULT_SPEED 100000
+#define UNIPHIER_I2C_MAX_SPEED 400000
+
+struct uniphier_i2c_priv {
+ struct completion comp;
+ struct i2c_adapter adap;
+ void __iomem *membase;
+ struct clk *clk;
+ unsigned int busy_cnt;
+};
+
+static irqreturn_t uniphier_i2c_interrupt(int irq, void *dev_id)
+{
+ struct uniphier_i2c_priv *priv = dev_id;
+
+ /*
+ * This hardware uses edge triggered interrupt. Do not touch the
+ * hardware registers in this handler to make sure to catch the next
+ * interrupt edge. Just send a complete signal and return.
+ */
+ complete(&priv->comp);
+
+ return IRQ_HANDLED;
+}
+
+static int uniphier_i2c_xfer_byte(struct i2c_adapter *adap, u32 txdata,
+ u32 *rxdatap)
+{
+ struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+ unsigned long time_left;
+ u32 rxdata;
+
+ reinit_completion(&priv->comp);
+
+ txdata |= UNIPHIER_I2C_DTRM_IRQEN;
+ dev_dbg(&adap->dev, "write data: 0x%04x\n", txdata);
+ writel(txdata, priv->membase + UNIPHIER_I2C_DTRM);
+
+ time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
+ if (unlikely(!time_left)) {
+ dev_err(&adap->dev, "transaction timeout\n");
+ return -ETIMEDOUT;
+ }
+
+ rxdata = readl(priv->membase + UNIPHIER_I2C_DREC);
+ dev_dbg(&adap->dev, "read data: 0x%04x\n", rxdata);
+
+ if (rxdatap)
+ *rxdatap = rxdata;
+
+ return 0;
+}
+
+static int uniphier_i2c_send_byte(struct i2c_adapter *adap, u32 txdata)
+{
+ u32 rxdata;
+ int ret;
+
+ ret = uniphier_i2c_xfer_byte(adap, txdata, &rxdata);
+ if (ret)
+ return ret;
+
+ if (unlikely(rxdata & UNIPHIER_I2C_DREC_LAB)) {
+ dev_dbg(&adap->dev, "arbitration lost\n");
+ return -EAGAIN;
+ }
+ if (unlikely(rxdata & UNIPHIER_I2C_DREC_LRB)) {
+ dev_dbg(&adap->dev, "could not get ACK\n");
+ return -ENXIO;
+ }
+
+ return 0;
+}
+
+static int uniphier_i2c_tx(struct i2c_adapter *adap, u16 addr, u16 len,
+ const u8 *buf)
+{
+ int ret;
+
+ dev_dbg(&adap->dev, "start condition\n");
+ ret = uniphier_i2c_send_byte(adap, addr << 1 |
+ UNIPHIER_I2C_DTRM_STA |
+ UNIPHIER_I2C_DTRM_NACK);
+ if (ret)
+ return ret;
+
+ while (len--) {
+ ret = uniphier_i2c_send_byte(adap,
+ UNIPHIER_I2C_DTRM_NACK | *buf++);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int uniphier_i2c_rx(struct i2c_adapter *adap, u16 addr, u16 len,
+ u8 *buf)
+{
+ int ret;
+
+ dev_dbg(&adap->dev, "start condition\n");
+ ret = uniphier_i2c_send_byte(adap, addr << 1 |
+ UNIPHIER_I2C_DTRM_STA |
+ UNIPHIER_I2C_DTRM_NACK |
+ UNIPHIER_I2C_DTRM_RD);
+ if (ret)
+ return ret;
+
+ while (len--) {
+ u32 rxdata;
+
+ ret = uniphier_i2c_xfer_byte(adap,
+ len ? 0 : UNIPHIER_I2C_DTRM_NACK,
+ &rxdata);
+ if (ret)
+ return ret;
+ *buf++ = rxdata;
+ }
+
+ return 0;
+}
+
+static int uniphier_i2c_stop(struct i2c_adapter *adap)
+{
+ dev_dbg(&adap->dev, "stop condition\n");
+ return uniphier_i2c_send_byte(adap, UNIPHIER_I2C_DTRM_STO |
+ UNIPHIER_I2C_DTRM_NACK);
+}
+
+static int uniphier_i2c_master_xfer_one(struct i2c_adapter *adap,
+ struct i2c_msg *msg, bool stop)
+{
+ bool is_read = msg->flags & I2C_M_RD;
+ bool recovery = false;
+ int ret;
+
+ dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n",
+ is_read ? "receive" : "transmit", msg->addr, msg->len, stop);
+
+ if (is_read)
+ ret = uniphier_i2c_rx(adap, msg->addr, msg->len, msg->buf);
+ else
+ ret = uniphier_i2c_tx(adap, msg->addr, msg->len, msg->buf);
+
+ if (ret == -EAGAIN) /* could not acquire bus. bail out without STOP */
+ return ret;
+
+ if (ret == -ETIMEDOUT) {
+ /* This error is fatal. Needs recovery. */
+ stop = false;
+ recovery = true;
+ }
+
+ if (stop) {
+ int ret2 = uniphier_i2c_stop(adap);
+
+ if (ret2) {
+ /* Failed to issue STOP. The bus needs recovery. */
+ recovery = true;
+ ret = ret ?: ret2;
+ }
+ }
+
+ if (recovery)
+ i2c_recover_bus(adap);
+
+ return ret;
+}
+
+static int uniphier_i2c_check_bus_busy(struct i2c_adapter *adap)
+{
+ struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+ if (!(readl(priv->membase + UNIPHIER_I2C_DREC) &
+ UNIPHIER_I2C_DREC_BBN)) {
+ if (priv->busy_cnt++ > 3) {
+ /*
+ * If bus busy continues too long, it is probably
+ * in a wrong state. Try bus recovery.
+ */
+ i2c_recover_bus(adap);
+ priv->busy_cnt = 0;
+ }
+
+ return -EAGAIN;
+ }
+
+ priv->busy_cnt = 0;
+ return 0;
+}
+
+static int uniphier_i2c_master_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ struct i2c_msg *msg, *emsg = msgs + num;
+ int ret;
+
+ ret = uniphier_i2c_check_bus_busy(adap);
+ if (ret)
+ return ret;
+
+ for (msg = msgs; msg < emsg; msg++) {
+ /* If next message is read, skip the stop condition */
+ bool stop = !(msg + 1 < emsg && msg[1].flags & I2C_M_RD);
+ /* but, force it if I2C_M_STOP is set */
+ if (msg->flags & I2C_M_STOP)
+ stop = true;
+
+ ret = uniphier_i2c_master_xfer_one(adap, msg, stop);
+ if (ret)
+ return ret;
+ }
+
+ return num;
+}
+
+static u32 uniphier_i2c_functionality(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm uniphier_i2c_algo = {
+ .master_xfer = uniphier_i2c_master_xfer,
+ .functionality = uniphier_i2c_functionality,
+};
+
+static void uniphier_i2c_reset(struct uniphier_i2c_priv *priv, bool reset_on)
+{
+ u32 val = UNIPHIER_I2C_BRST_RSCL;
+
+ val |= reset_on ? 0 : UNIPHIER_I2C_BRST_FOEN;
+ writel(val, priv->membase + UNIPHIER_I2C_BRST);
+}
+
+static int uniphier_i2c_get_scl(struct i2c_adapter *adap)
+{
+ struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+ return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
+ UNIPHIER_I2C_BSTS_SCL);
+}
+
+static void uniphier_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+ struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+ writel(val ? UNIPHIER_I2C_BRST_RSCL : 0,
+ priv->membase + UNIPHIER_I2C_BRST);
+}
+
+static int uniphier_i2c_get_sda(struct i2c_adapter *adap)
+{
+ struct uniphier_i2c_priv *priv = i2c_get_adapdata(adap);
+
+ return !!(readl(priv->membase + UNIPHIER_I2C_BSTS) &
+ UNIPHIER_I2C_BSTS_SDA);
+}
+
+static void uniphier_i2c_unprepare_recovery(struct i2c_adapter *adap)
+{
+ uniphier_i2c_reset(i2c_get_adapdata(adap), false);
+}
+
+static struct i2c_bus_recovery_info uniphier_i2c_bus_recovery_info = {
+ .recover_bus = i2c_generic_scl_recovery,
+ .get_scl = uniphier_i2c_get_scl,
+ .set_scl = uniphier_i2c_set_scl,
+ .get_sda = uniphier_i2c_get_sda,
+ .unprepare_recovery = uniphier_i2c_unprepare_recovery,
+};
+
+static int uniphier_i2c_clk_init(struct device *dev,
+ struct uniphier_i2c_priv *priv)
+{
+ struct device_node *np = dev->of_node;
+ unsigned long clk_rate;
+ u32 bus_speed;
+ int ret;
+
+ if (of_property_read_u32(np, "clock-frequency", &bus_speed))
+ bus_speed = UNIPHIER_I2C_DEFAULT_SPEED;
+
+ if (bus_speed > UNIPHIER_I2C_MAX_SPEED)
+ bus_speed = UNIPHIER_I2C_MAX_SPEED;
+
+ /* Get input clk rate through clk driver */
+ priv->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(priv->clk)) {
+ dev_err(dev, "failed to get clock\n");
+ return PTR_ERR(priv->clk);
+ }
+
+ ret = clk_prepare_enable(priv->clk);
+ if (ret)
+ return ret;
+
+ clk_rate = clk_get_rate(priv->clk);
+
+ uniphier_i2c_reset(priv, true);
+
+ writel((clk_rate / bus_speed / 2 << 16) | (clk_rate / bus_speed),
+ priv->membase + UNIPHIER_I2C_CLK);
+
+ uniphier_i2c_reset(priv, false);
+
+ return 0;
+}
+
+static int uniphier_i2c_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct uniphier_i2c_priv *priv;
+ struct resource *regs;
+ int irq;
+ int ret;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ priv->membase = devm_ioremap_resource(dev, regs);
+ if (IS_ERR(priv->membase))
+ return PTR_ERR(priv->membase);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0) {
+ dev_err(dev, "failed to get IRQ number");
+ return irq;
+ }
+
+ init_completion(&priv->comp);
+ priv->adap.owner = THIS_MODULE;
+ priv->adap.algo = &uniphier_i2c_algo;
+ priv->adap.dev.parent = dev;
+ priv->adap.dev.of_node = dev->of_node;
+ strlcpy(priv->adap.name, "UniPhier I2C", sizeof(priv->adap.name));
+ priv->adap.bus_recovery_info = &uniphier_i2c_bus_recovery_info;
+ i2c_set_adapdata(&priv->adap, priv);
+ platform_set_drvdata(pdev, priv);
+
+ ret = uniphier_i2c_clk_init(dev, priv);
+ if (ret)
+ return ret;
+
+ ret = devm_request_irq(dev, irq, uniphier_i2c_interrupt, 0, pdev->name,
+ priv);
+ if (ret) {
+ dev_err(dev, "failed to request irq %d\n", irq);
+ goto err;
+ }
+
+ ret = i2c_add_adapter(&priv->adap);
+ if (ret) {
+ dev_err(dev, "failed to add I2C adapter\n");
+ goto err;
+ }
+
+err:
+ if (ret)
+ clk_disable_unprepare(priv->clk);
+
+ return ret;
+}
+
+static int uniphier_i2c_remove(struct platform_device *pdev)
+{
+ struct uniphier_i2c_priv *priv = platform_get_drvdata(pdev);
+
+ i2c_del_adapter(&priv->adap);
+ clk_disable_unprepare(priv->clk);
+
+ return 0;
+}
+
+static const struct of_device_id uniphier_i2c_match[] = {
+ { .compatible = "socionext,uniphier-i2c" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, uniphier_i2c_match);
+
+static struct platform_driver uniphier_i2c_drv = {
+ .probe = uniphier_i2c_probe,
+ .remove = uniphier_i2c_remove,
+ .driver = {
+ .name = "uniphier-i2c",
+ .of_match_table = uniphier_i2c_match,
+ },
+};
+module_platform_driver(uniphier_i2c_drv);
+
+MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
+MODULE_DESCRIPTION("UniPhier I2C bus driver");
+MODULE_LICENSE("GPL");
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