--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Loongson-2K/Loongson LS7A I2C master mode driver
+ *
+ * Copyright (C) 2013 Loongson Technology Corporation Limited.
+ * Copyright (C) 2014-2017 Lemote, Inc.
+ * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
+ *
+ * Originally written by liushaozong
+ * Rewritten for mainline by Binbin Zhou <zhoubinbin@loongson.cn>
+ */
+
+#include <linux/bits.h>
+#include <linux/completion.h>
+#include <linux/device.h>
+#include <linux/iopoll.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/pm_runtime.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/units.h>
+
+/* I2C Registers */
+#define I2C_LS2X_PRER 0x0 /* Freq Division Register(16 bits) */
+#define I2C_LS2X_CTR 0x2 /* Control Register */
+#define I2C_LS2X_TXR 0x3 /* Transport Data Register */
+#define I2C_LS2X_RXR 0x3 /* Receive Data Register */
+#define I2C_LS2X_CR 0x4 /* Command Control Register */
+#define I2C_LS2X_SR 0x4 /* State Register */
+
+/* Command Control Register Bit */
+#define LS2X_CR_START BIT(7) /* Start signal */
+#define LS2X_CR_STOP BIT(6) /* Stop signal */
+#define LS2X_CR_READ BIT(5) /* Read signal */
+#define LS2X_CR_WRITE BIT(4) /* Write signal */
+#define LS2X_CR_ACK BIT(3) /* Response signal */
+#define LS2X_CR_IACK BIT(0) /* Interrupt response signal */
+
+/* State Register Bit */
+#define LS2X_SR_NOACK BIT(7) /* Receive NACK */
+#define LS2X_SR_BUSY BIT(6) /* Bus busy state */
+#define LS2X_SR_AL BIT(5) /* Arbitration lost */
+#define LS2X_SR_TIP BIT(1) /* Transmission state */
+#define LS2X_SR_IF BIT(0) /* Interrupt flag */
+
+/* Control Register Bit */
+#define LS2X_CTR_EN BIT(7) /* 0: I2c frequency setting 1: Normal */
+#define LS2X_CTR_IEN BIT(6) /* Enable i2c interrupt */
+#define LS2X_CTR_MST BIT(5) /* 0: Slave mode 1: Master mode */
+#define CTR_FREQ_MASK GENMASK(7, 6)
+#define CTR_READY_MASK GENMASK(7, 5)
+
+/* The PCLK frequency from LPB */
+#define LS2X_I2C_PCLK_FREQ (50 * HZ_PER_MHZ)
+
+/* The default bus frequency, which is an empirical value */
+#define LS2X_I2C_FREQ_STD (33 * HZ_PER_KHZ)
+
+struct ls2x_i2c_priv {
+ struct i2c_adapter adapter;
+ void __iomem *base;
+ struct i2c_timings i2c_t;
+ struct completion cmd_complete;
+};
+
+/*
+ * Interrupt service routine.
+ * This gets called whenever an I2C interrupt occurs.
+ */
+static irqreturn_t ls2x_i2c_isr(int this_irq, void *dev_id)
+{
+ struct ls2x_i2c_priv *priv = dev_id;
+
+ if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))
+ return IRQ_NONE;
+
+ writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);
+ complete(&priv->cmd_complete);
+ return IRQ_HANDLED;
+}
+
+/*
+ * The ls2x i2c controller supports standard mode and fast mode, so the
+ * maximum bus frequency is '400kHz'.
+ * The bus frequency is set to the empirical value of '33KHz' by default,
+ * but it can also be taken from ACPI or FDT for compatibility with more
+ * devices.
+ */
+static void ls2x_i2c_adjust_bus_speed(struct ls2x_i2c_priv *priv)
+{
+ struct i2c_timings *t = &priv->i2c_t;
+ struct device *dev = priv->adapter.dev.parent;
+ u32 acpi_speed = i2c_acpi_find_bus_speed(dev);
+
+ i2c_parse_fw_timings(dev, t, false);
+
+ if (acpi_speed || t->bus_freq_hz)
+ t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);
+ else
+ t->bus_freq_hz = LS2X_I2C_FREQ_STD;
+
+ /* Calculate and set i2c frequency. */
+ writew(LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1,
+ priv->base + I2C_LS2X_PRER);
+}
+
+static void ls2x_i2c_init(struct ls2x_i2c_priv *priv)
+{
+ /* Set i2c frequency setting mode and disable interrupts. */
+ writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,
+ priv->base + I2C_LS2X_CTR);
+
+ ls2x_i2c_adjust_bus_speed(priv);
+
+ /* Set i2c normal operating mode and enable interrupts. */
+ writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,
+ priv->base + I2C_LS2X_CTR);
+}
+
+static int ls2x_i2c_xfer_byte(struct ls2x_i2c_priv *priv, u8 txdata, u8 *rxdatap)
+{
+ u8 rxdata;
+ unsigned long time_left;
+
+ writeb(txdata, priv->base + I2C_LS2X_CR);
+
+ time_left = wait_for_completion_timeout(&priv->cmd_complete,
+ priv->adapter.timeout);
+ if (!time_left)
+ return -ETIMEDOUT;
+
+ rxdata = readb(priv->base + I2C_LS2X_SR);
+ if (rxdatap)
+ *rxdatap = rxdata;
+
+ return 0;
+}
+
+static int ls2x_i2c_send_byte(struct ls2x_i2c_priv *priv, u8 txdata)
+{
+ int ret;
+ u8 rxdata;
+
+ ret = ls2x_i2c_xfer_byte(priv, txdata, &rxdata);
+ if (ret)
+ return ret;
+
+ if (rxdata & LS2X_SR_AL)
+ return -EAGAIN;
+
+ if (rxdata & LS2X_SR_NOACK)
+ return -ENXIO;
+
+ return 0;
+}
+
+static int ls2x_i2c_stop(struct ls2x_i2c_priv *priv)
+{
+ u8 value;
+
+ writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);
+ return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,
+ !(value & LS2X_SR_BUSY), 100,
+ jiffies_to_usecs(priv->adapter.timeout));
+}
+
+static int ls2x_i2c_start(struct ls2x_i2c_priv *priv, struct i2c_msg *msgs)
+{
+ reinit_completion(&priv->cmd_complete);
+
+ writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);
+ return ls2x_i2c_send_byte(priv, LS2X_CR_START | LS2X_CR_WRITE);
+}
+
+static int ls2x_i2c_rx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
+{
+ int ret;
+ u8 rxdata, *buf = msg->buf;
+ u16 len = msg->len;
+
+ /* Contains steps to send start condition and address. */
+ ret = ls2x_i2c_start(priv, msg);
+ if (ret)
+ return ret;
+
+ while (len--) {
+ ret = ls2x_i2c_xfer_byte(priv,
+ LS2X_CR_READ | (len ? 0 : LS2X_CR_ACK),
+ &rxdata);
+ if (ret)
+ return ret;
+
+ *buf++ = readb(priv->base + I2C_LS2X_RXR);
+ }
+
+ return 0;
+}
+
+static int ls2x_i2c_tx(struct ls2x_i2c_priv *priv, struct i2c_msg *msg)
+{
+ int ret;
+ u8 *buf = msg->buf;
+ u16 len = msg->len;
+
+ /* Contains steps to send start condition and address. */
+ ret = ls2x_i2c_start(priv, msg);
+ if (ret)
+ return ret;
+
+ while (len--) {
+ writeb(*buf++, priv->base + I2C_LS2X_TXR);
+
+ ret = ls2x_i2c_send_byte(priv, LS2X_CR_WRITE);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+static int ls2x_i2c_xfer_one(struct ls2x_i2c_priv *priv,
+ struct i2c_msg *msg, bool stop)
+{
+ int ret;
+
+ if (msg->flags & I2C_M_RD)
+ ret = ls2x_i2c_rx(priv, msg);
+ else
+ ret = ls2x_i2c_tx(priv, msg);
+
+ if (ret < 0) {
+ /* Fatel error. Needs reinit. */
+ if (ret == -ETIMEDOUT)
+ ls2x_i2c_init(priv);
+
+ return ret;
+ }
+
+ if (stop) {
+ /* Failed to issue STOP. Needs reinit. */
+ ret = ls2x_i2c_stop(priv);
+ if (ret)
+ ls2x_i2c_init(priv);
+ }
+
+ return ret;
+}
+
+static int ls2x_i2c_master_xfer(struct i2c_adapter *adap,
+ struct i2c_msg *msgs, int num)
+{
+ int ret;
+ struct i2c_msg *msg, *emsg = msgs + num;
+ struct ls2x_i2c_priv *priv = i2c_get_adapdata(adap);
+
+ for (msg = msgs; msg < emsg; msg++) {
+ ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);
+ if (ret)
+ return ret;
+ }
+
+ return num;
+}
+
+static unsigned int ls2x_i2c_func(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm ls2x_i2c_algo = {
+ .master_xfer = ls2x_i2c_master_xfer,
+ .functionality = ls2x_i2c_func,
+};
+
+static int ls2x_i2c_probe(struct platform_device *pdev)
+{
+ int ret, irq;
+ struct i2c_adapter *adap;
+ struct ls2x_i2c_priv *priv;
+ struct device *dev = &pdev->dev;
+
+ priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ /* Map hardware registers */
+ priv->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->base))
+ return PTR_ERR(priv->base);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq < 0)
+ return irq;
+
+ /* Add the i2c adapter */
+ adap = &priv->adapter;
+ adap->retries = 5;
+ adap->nr = pdev->id;
+ adap->dev.parent = dev;
+ adap->owner = THIS_MODULE;
+ adap->algo = &ls2x_i2c_algo;
+ adap->timeout = msecs_to_jiffies(100);
+ device_set_node(&adap->dev, dev_fwnode(dev));
+ i2c_set_adapdata(adap, priv);
+ strscpy(adap->name, pdev->name, sizeof(adap->name));
+ init_completion(&priv->cmd_complete);
+ platform_set_drvdata(pdev, priv);
+
+ ls2x_i2c_init(priv);
+
+ ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",
+ priv);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Unable to request irq %d\n", irq);
+
+ return devm_i2c_add_adapter(dev, adap);
+}
+
+static int ls2x_i2c_suspend(struct device *dev)
+{
+ struct ls2x_i2c_priv *priv = dev_get_drvdata(dev);
+
+ /* Disable interrupts */
+ writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,
+ priv->base + I2C_LS2X_CTR);
+
+ return 0;
+}
+
+static int ls2x_i2c_resume(struct device *dev)
+{
+ ls2x_i2c_init(dev_get_drvdata(dev));
+ return 0;
+}
+
+static DEFINE_RUNTIME_DEV_PM_OPS(ls2x_i2c_pm_ops,
+ ls2x_i2c_suspend, ls2x_i2c_resume, NULL);
+
+static const struct of_device_id ls2x_i2c_id_table[] = {
+ { .compatible = "loongson,ls2k-i2c" },
+ { .compatible = "loongson,ls7a-i2c" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, ls2x_i2c_id_table);
+
+static const struct acpi_device_id ls2x_i2c_acpi_match[] = {
+ { "LOON0004" }, /* Loongson LS7A */
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, ls2x_i2c_acpi_match);
+
+static struct platform_driver ls2x_i2c_driver = {
+ .probe = ls2x_i2c_probe,
+ .driver = {
+ .name = "ls2x-i2c",
+ .pm = pm_sleep_ptr(&ls2x_i2c_pm_ops),
+ .of_match_table = ls2x_i2c_id_table,
+ .acpi_match_table = ls2x_i2c_acpi_match,
+ },
+};
+module_platform_driver(ls2x_i2c_driver);
+
+MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");
+MODULE_AUTHOR("Loongson Technology Corporation Limited");
+MODULE_LICENSE("GPL");
projects / platform / kernel / linux-rpi.git / commitdiff