diff options
Diffstat (limited to 'kernel/drivers/i2c/busses/i2c-uniphier-f.c')
-rw-r--r-- | kernel/drivers/i2c/busses/i2c-uniphier-f.c | 584 |
1 files changed, 584 insertions, 0 deletions
diff --git a/kernel/drivers/i2c/busses/i2c-uniphier-f.c b/kernel/drivers/i2c/busses/i2c-uniphier-f.c new file mode 100644 index 000000000..e8d03bcfe --- /dev/null +++ b/kernel/drivers/i2c/busses/i2c-uniphier-f.c @@ -0,0 +1,584 @@ +/* + * 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_FI2C_CR 0x00 /* control register */ +#define UNIPHIER_FI2C_CR_MST BIT(3) /* master mode */ +#define UNIPHIER_FI2C_CR_STA BIT(2) /* start condition */ +#define UNIPHIER_FI2C_CR_STO BIT(1) /* stop condition */ +#define UNIPHIER_FI2C_CR_NACK BIT(0) /* do not return ACK */ +#define UNIPHIER_FI2C_DTTX 0x04 /* TX FIFO */ +#define UNIPHIER_FI2C_DTTX_CMD BIT(8) /* send command (slave addr) */ +#define UNIPHIER_FI2C_DTTX_RD BIT(0) /* read transaction */ +#define UNIPHIER_FI2C_DTRX 0x04 /* RX FIFO */ +#define UNIPHIER_FI2C_SLAD 0x0c /* slave address */ +#define UNIPHIER_FI2C_CYC 0x10 /* clock cycle control */ +#define UNIPHIER_FI2C_LCTL 0x14 /* clock low period control */ +#define UNIPHIER_FI2C_SSUT 0x18 /* restart/stop setup time control */ +#define UNIPHIER_FI2C_DSUT 0x1c /* data setup time control */ +#define UNIPHIER_FI2C_INT 0x20 /* interrupt status */ +#define UNIPHIER_FI2C_IE 0x24 /* interrupt enable */ +#define UNIPHIER_FI2C_IC 0x28 /* interrupt clear */ +#define UNIPHIER_FI2C_INT_TE BIT(9) /* TX FIFO empty */ +#define UNIPHIER_FI2C_INT_RF BIT(8) /* RX FIFO full */ +#define UNIPHIER_FI2C_INT_TC BIT(7) /* send complete (STOP) */ +#define UNIPHIER_FI2C_INT_RC BIT(6) /* receive complete (STOP) */ +#define UNIPHIER_FI2C_INT_TB BIT(5) /* sent specified bytes */ +#define UNIPHIER_FI2C_INT_RB BIT(4) /* received specified bytes */ +#define UNIPHIER_FI2C_INT_NA BIT(2) /* no ACK */ +#define UNIPHIER_FI2C_INT_AL BIT(1) /* arbitration lost */ +#define UNIPHIER_FI2C_SR 0x2c /* status register */ +#define UNIPHIER_FI2C_SR_DB BIT(12) /* device busy */ +#define UNIPHIER_FI2C_SR_STS BIT(11) /* stop condition detected */ +#define UNIPHIER_FI2C_SR_BB BIT(8) /* bus busy */ +#define UNIPHIER_FI2C_SR_RFF BIT(3) /* RX FIFO full */ +#define UNIPHIER_FI2C_SR_RNE BIT(2) /* RX FIFO not empty */ +#define UNIPHIER_FI2C_SR_TNF BIT(1) /* TX FIFO not full */ +#define UNIPHIER_FI2C_SR_TFE BIT(0) /* TX FIFO empty */ +#define UNIPHIER_FI2C_RST 0x34 /* reset control */ +#define UNIPHIER_FI2C_RST_TBRST BIT(2) /* clear TX FIFO */ +#define UNIPHIER_FI2C_RST_RBRST BIT(1) /* clear RX FIFO */ +#define UNIPHIER_FI2C_RST_RST BIT(0) /* forcible bus reset */ +#define UNIPHIER_FI2C_BM 0x38 /* bus monitor */ +#define UNIPHIER_FI2C_BM_SDAO BIT(3) /* output for SDA line */ +#define UNIPHIER_FI2C_BM_SDAS BIT(2) /* readback of SDA line */ +#define UNIPHIER_FI2C_BM_SCLO BIT(1) /* output for SCL line */ +#define UNIPHIER_FI2C_BM_SCLS BIT(0) /* readback of SCL line */ +#define UNIPHIER_FI2C_NOISE 0x3c /* noise filter control */ +#define UNIPHIER_FI2C_TBC 0x40 /* TX byte count setting */ +#define UNIPHIER_FI2C_RBC 0x44 /* RX byte count setting */ +#define UNIPHIER_FI2C_TBCM 0x48 /* TX byte count monitor */ +#define UNIPHIER_FI2C_RBCM 0x4c /* RX byte count monitor */ +#define UNIPHIER_FI2C_BRST 0x50 /* bus reset */ +#define UNIPHIER_FI2C_BRST_FOEN BIT(1) /* normal operation */ +#define UNIPHIER_FI2C_BRST_RSCL BIT(0) /* release SCL */ + +#define UNIPHIER_FI2C_INT_FAULTS \ + (UNIPHIER_FI2C_INT_NA | UNIPHIER_FI2C_INT_AL) +#define UNIPHIER_FI2C_INT_STOP \ + (UNIPHIER_FI2C_INT_TC | UNIPHIER_FI2C_INT_RC) + +#define UNIPHIER_FI2C_RD BIT(0) +#define UNIPHIER_FI2C_STOP BIT(1) +#define UNIPHIER_FI2C_MANUAL_NACK BIT(2) +#define UNIPHIER_FI2C_BYTE_WISE BIT(3) +#define UNIPHIER_FI2C_DEFER_STOP_COMP BIT(4) + +#define UNIPHIER_FI2C_DEFAULT_SPEED 100000 +#define UNIPHIER_FI2C_MAX_SPEED 400000 +#define UNIPHIER_FI2C_FIFO_SIZE 8 + +struct uniphier_fi2c_priv { + struct completion comp; + struct i2c_adapter adap; + void __iomem *membase; + struct clk *clk; + unsigned int len; + u8 *buf; + u32 enabled_irqs; + int error; + unsigned int flags; + unsigned int busy_cnt; +}; + +static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv, + bool first) +{ + int fifo_space = UNIPHIER_FI2C_FIFO_SIZE; + + /* + * TX-FIFO stores slave address in it for the first access. + * Decrement the counter. + */ + if (first) + fifo_space--; + + while (priv->len) { + if (fifo_space-- <= 0) + break; + + dev_dbg(&priv->adap.dev, "write data: %02x\n", *priv->buf); + writel(*priv->buf++, priv->membase + UNIPHIER_FI2C_DTTX); + priv->len--; + } +} + +static void uniphier_fi2c_drain_rxfifo(struct uniphier_fi2c_priv *priv) +{ + int fifo_left = priv->flags & UNIPHIER_FI2C_BYTE_WISE ? + 1 : UNIPHIER_FI2C_FIFO_SIZE; + + while (priv->len) { + if (fifo_left-- <= 0) + break; + + *priv->buf++ = readl(priv->membase + UNIPHIER_FI2C_DTRX); + dev_dbg(&priv->adap.dev, "read data: %02x\n", priv->buf[-1]); + priv->len--; + } +} + +static void uniphier_fi2c_set_irqs(struct uniphier_fi2c_priv *priv) +{ + writel(priv->enabled_irqs, priv->membase + UNIPHIER_FI2C_IE); +} + +static void uniphier_fi2c_clear_irqs(struct uniphier_fi2c_priv *priv) +{ + writel(-1, priv->membase + UNIPHIER_FI2C_IC); +} + +static void uniphier_fi2c_stop(struct uniphier_fi2c_priv *priv) +{ + dev_dbg(&priv->adap.dev, "stop condition\n"); + + priv->enabled_irqs |= UNIPHIER_FI2C_INT_STOP; + uniphier_fi2c_set_irqs(priv); + writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STO, + priv->membase + UNIPHIER_FI2C_CR); +} + +static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id) +{ + struct uniphier_fi2c_priv *priv = dev_id; + u32 irq_status; + + irq_status = readl(priv->membase + UNIPHIER_FI2C_INT); + + dev_dbg(&priv->adap.dev, + "interrupt: enabled_irqs=%04x, irq_status=%04x\n", + priv->enabled_irqs, irq_status); + + if (irq_status & UNIPHIER_FI2C_INT_STOP) + goto complete; + + if (unlikely(irq_status & UNIPHIER_FI2C_INT_AL)) { + dev_dbg(&priv->adap.dev, "arbitration lost\n"); + priv->error = -EAGAIN; + goto complete; + } + + if (unlikely(irq_status & UNIPHIER_FI2C_INT_NA)) { + dev_dbg(&priv->adap.dev, "could not get ACK\n"); + priv->error = -ENXIO; + if (priv->flags & UNIPHIER_FI2C_RD) { + /* + * work around a hardware bug: + * The receive-completed interrupt is never set even if + * STOP condition is detected after the address phase + * of read transaction fails to get ACK. + * To avoid time-out error, we issue STOP here, + * but do not wait for its completion. + * It should be checked after exiting this handler. + */ + uniphier_fi2c_stop(priv); + priv->flags |= UNIPHIER_FI2C_DEFER_STOP_COMP; + goto complete; + } + goto stop; + } + + if (irq_status & UNIPHIER_FI2C_INT_TE) { + if (!priv->len) + goto data_done; + + uniphier_fi2c_fill_txfifo(priv, false); + goto handled; + } + + if (irq_status & (UNIPHIER_FI2C_INT_RF | UNIPHIER_FI2C_INT_RB)) { + uniphier_fi2c_drain_rxfifo(priv); + if (!priv->len) + goto data_done; + + if (unlikely(priv->flags & UNIPHIER_FI2C_MANUAL_NACK)) { + if (priv->len <= UNIPHIER_FI2C_FIFO_SIZE && + !(priv->flags & UNIPHIER_FI2C_BYTE_WISE)) { + dev_dbg(&priv->adap.dev, + "enable read byte count IRQ\n"); + priv->enabled_irqs |= UNIPHIER_FI2C_INT_RB; + uniphier_fi2c_set_irqs(priv); + priv->flags |= UNIPHIER_FI2C_BYTE_WISE; + } + if (priv->len <= 1) { + dev_dbg(&priv->adap.dev, "set NACK\n"); + writel(UNIPHIER_FI2C_CR_MST | + UNIPHIER_FI2C_CR_NACK, + priv->membase + UNIPHIER_FI2C_CR); + } + } + + goto handled; + } + + return IRQ_NONE; + +data_done: + if (priv->flags & UNIPHIER_FI2C_STOP) { +stop: + uniphier_fi2c_stop(priv); + } else { +complete: + priv->enabled_irqs = 0; + uniphier_fi2c_set_irqs(priv); + complete(&priv->comp); + } + +handled: + uniphier_fi2c_clear_irqs(priv); + + return IRQ_HANDLED; +} + +static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr) +{ + priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE; + /* do not use TX byte counter */ + writel(0, priv->membase + UNIPHIER_FI2C_TBC); + /* set slave address */ + writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1, + priv->membase + UNIPHIER_FI2C_DTTX); + /* first chunk of data */ + uniphier_fi2c_fill_txfifo(priv, true); +} + +static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr) +{ + priv->flags |= UNIPHIER_FI2C_RD; + + if (likely(priv->len < 256)) { + /* + * If possible, use RX byte counter. + * It can automatically handle NACK for the last byte. + */ + writel(priv->len, priv->membase + UNIPHIER_FI2C_RBC); + priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF | + UNIPHIER_FI2C_INT_RB; + } else { + /* + * The byte counter can not count over 256. In this case, + * do not use it at all. Drain data when FIFO gets full, + * but treat the last portion as a special case. + */ + writel(0, priv->membase + UNIPHIER_FI2C_RBC); + priv->flags |= UNIPHIER_FI2C_MANUAL_NACK; + priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF; + } + + /* set slave address with RD bit */ + writel(UNIPHIER_FI2C_DTTX_CMD | UNIPHIER_FI2C_DTTX_RD | addr << 1, + priv->membase + UNIPHIER_FI2C_DTTX); +} + +static void uniphier_fi2c_reset(struct uniphier_fi2c_priv *priv) +{ + writel(UNIPHIER_FI2C_RST_RST, priv->membase + UNIPHIER_FI2C_RST); +} + +static void uniphier_fi2c_prepare_operation(struct uniphier_fi2c_priv *priv) +{ + writel(UNIPHIER_FI2C_BRST_FOEN | UNIPHIER_FI2C_BRST_RSCL, + priv->membase + UNIPHIER_FI2C_BRST); +} + +static void uniphier_fi2c_recover(struct uniphier_fi2c_priv *priv) +{ + uniphier_fi2c_reset(priv); + i2c_recover_bus(&priv->adap); +} + +static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap, + struct i2c_msg *msg, bool stop) +{ + struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); + bool is_read = msg->flags & I2C_M_RD; + unsigned long time_left; + + dev_dbg(&adap->dev, "%s: addr=0x%02x, len=%d, stop=%d\n", + is_read ? "receive" : "transmit", msg->addr, msg->len, stop); + + priv->len = msg->len; + priv->buf = msg->buf; + priv->enabled_irqs = UNIPHIER_FI2C_INT_FAULTS; + priv->error = 0; + priv->flags = 0; + + if (stop) + priv->flags |= UNIPHIER_FI2C_STOP; + + reinit_completion(&priv->comp); + uniphier_fi2c_clear_irqs(priv); + writel(UNIPHIER_FI2C_RST_TBRST | UNIPHIER_FI2C_RST_RBRST, + priv->membase + UNIPHIER_FI2C_RST); /* reset TX/RX FIFO */ + + if (is_read) + uniphier_fi2c_rx_init(priv, msg->addr); + else + uniphier_fi2c_tx_init(priv, msg->addr); + + uniphier_fi2c_set_irqs(priv); + + dev_dbg(&adap->dev, "start condition\n"); + writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STA, + priv->membase + UNIPHIER_FI2C_CR); + + time_left = wait_for_completion_timeout(&priv->comp, adap->timeout); + if (!time_left) { + dev_err(&adap->dev, "transaction timeout.\n"); + uniphier_fi2c_recover(priv); + return -ETIMEDOUT; + } + dev_dbg(&adap->dev, "complete\n"); + + if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) { + u32 status = readl(priv->membase + UNIPHIER_FI2C_SR); + + if (!(status & UNIPHIER_FI2C_SR_STS) || + status & UNIPHIER_FI2C_SR_BB) { + dev_err(&adap->dev, + "stop condition was not completed.\n"); + uniphier_fi2c_recover(priv); + return -EBUSY; + } + } + + return priv->error; +} + +static int uniphier_fi2c_check_bus_busy(struct i2c_adapter *adap) +{ + struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); + + if (readl(priv->membase + UNIPHIER_FI2C_SR) & UNIPHIER_FI2C_SR_DB) { + if (priv->busy_cnt++ > 3) { + /* + * If bus busy continues too long, it is probably + * in a wrong state. Try bus recovery. + */ + uniphier_fi2c_recover(priv); + priv->busy_cnt = 0; + } + + return -EAGAIN; + } + + priv->busy_cnt = 0; + return 0; +} + +static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + struct i2c_msg *msg, *emsg = msgs + num; + int ret; + + ret = uniphier_fi2c_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_fi2c_master_xfer_one(adap, msg, stop); + if (ret) + return ret; + } + + return num; +} + +static u32 uniphier_fi2c_functionality(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static const struct i2c_algorithm uniphier_fi2c_algo = { + .master_xfer = uniphier_fi2c_master_xfer, + .functionality = uniphier_fi2c_functionality, +}; + +static int uniphier_fi2c_get_scl(struct i2c_adapter *adap) +{ + struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); + + return !!(readl(priv->membase + UNIPHIER_FI2C_BM) & + UNIPHIER_FI2C_BM_SCLS); +} + +static void uniphier_fi2c_set_scl(struct i2c_adapter *adap, int val) +{ + struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); + + writel(val ? UNIPHIER_FI2C_BRST_RSCL : 0, + priv->membase + UNIPHIER_FI2C_BRST); +} + +static int uniphier_fi2c_get_sda(struct i2c_adapter *adap) +{ + struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap); + + return !!(readl(priv->membase + UNIPHIER_FI2C_BM) & + UNIPHIER_FI2C_BM_SDAS); +} + +static void uniphier_fi2c_unprepare_recovery(struct i2c_adapter *adap) +{ + uniphier_fi2c_prepare_operation(i2c_get_adapdata(adap)); +} + +static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = { + .recover_bus = i2c_generic_scl_recovery, + .get_scl = uniphier_fi2c_get_scl, + .set_scl = uniphier_fi2c_set_scl, + .get_sda = uniphier_fi2c_get_sda, + .unprepare_recovery = uniphier_fi2c_unprepare_recovery, +}; + +static int uniphier_fi2c_clk_init(struct device *dev, + struct uniphier_fi2c_priv *priv) +{ + struct device_node *np = dev->of_node; + unsigned long clk_rate; + u32 bus_speed, clk_count; + int ret; + + if (of_property_read_u32(np, "clock-frequency", &bus_speed)) + bus_speed = UNIPHIER_FI2C_DEFAULT_SPEED; + + if (bus_speed > UNIPHIER_FI2C_MAX_SPEED) + bus_speed = UNIPHIER_FI2C_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_fi2c_reset(priv); + + clk_count = clk_rate / bus_speed; + + writel(clk_count, priv->membase + UNIPHIER_FI2C_CYC); + writel(clk_count / 2, priv->membase + UNIPHIER_FI2C_LCTL); + writel(clk_count / 2, priv->membase + UNIPHIER_FI2C_SSUT); + writel(clk_count / 16, priv->membase + UNIPHIER_FI2C_DSUT); + + uniphier_fi2c_prepare_operation(priv); + + return 0; +} + +static int uniphier_fi2c_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct uniphier_fi2c_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_fi2c_algo; + priv->adap.dev.parent = dev; + priv->adap.dev.of_node = dev->of_node; + strlcpy(priv->adap.name, "UniPhier FI2C", sizeof(priv->adap.name)); + priv->adap.bus_recovery_info = &uniphier_fi2c_bus_recovery_info; + i2c_set_adapdata(&priv->adap, priv); + platform_set_drvdata(pdev, priv); + + ret = uniphier_fi2c_clk_init(dev, priv); + if (ret) + return ret; + + ret = devm_request_irq(dev, irq, uniphier_fi2c_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_fi2c_remove(struct platform_device *pdev) +{ + struct uniphier_fi2c_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_fi2c_match[] = { + { .compatible = "socionext,uniphier-fi2c" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, uniphier_fi2c_match); + +static struct platform_driver uniphier_fi2c_drv = { + .probe = uniphier_fi2c_probe, + .remove = uniphier_fi2c_remove, + .driver = { + .name = "uniphier-fi2c", + .of_match_table = uniphier_fi2c_match, + }, +}; +module_platform_driver(uniphier_fi2c_drv); + +MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>"); +MODULE_DESCRIPTION("UniPhier FIFO-builtin I2C bus driver"); +MODULE_LICENSE("GPL"); |