diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-ls2x.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-ls2x.c | 370 |
1 files changed, 370 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-ls2x.c b/drivers/i2c/busses/i2c-ls2x.c new file mode 100644 index 0000000000..ebae603570 --- /dev/null +++ b/drivers/i2c/busses/i2c-ls2x.c @@ -0,0 +1,370 @@ +// 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"); |