This driver assumes that an interrupt line is always available for the I2C master. This is not always the case and this patch adds support for a polling version based on workqueue.
Signed-off-by: Federico Vaga <[email protected]> --- drivers/i2c/busses/i2c-ocores.c | 94 ++++++++++++++++++++++++++++++++++------- 1 file changed, 79 insertions(+), 15 deletions(-) diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c index 274d6eb22a2c..0dad1a512ef5 100644 --- a/drivers/i2c/busses/i2c-ocores.c +++ b/drivers/i2c/busses/i2c-ocores.c @@ -13,6 +13,7 @@ */ #include <linux/clk.h> +#include <linux/delay.h> #include <linux/err.h> #include <linux/kernel.h> #include <linux/module.h> @@ -26,14 +27,19 @@ #include <linux/io.h> #include <linux/log2.h> #include <linux/spinlock.h> +#include <linux/workqueue.h> + +#define OCORES_FLAG_POLL BIT(0) struct ocores_i2c { void __iomem *base; u32 reg_shift; u32 reg_io_width; + unsigned long flags; wait_queue_head_t wait; struct i2c_adapter adap; struct i2c_msg *msg; + struct work_struct xfer_work; int pos; int nmsgs; int state; /* see STATE_ */ @@ -166,8 +172,9 @@ static void ocores_process(struct ocores_i2c *i2c, u8 stat) oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP); return; } - } else + } else { msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA); + } /* end of msg? */ if (i2c->pos == msg->len) { @@ -232,6 +239,50 @@ static irqreturn_t ocores_isr(int irq, void *dev_id) return IRQ_HANDLED; } + +/** + * It waits until is possible to process some data + * @i2c: ocores I2C device instance + * + * This is used when the device is in polling mode (interrupts disabled). + * It sleeps for the time necessary to send 8bits (one transfer over + * the I2C bus), then it permanently ping the ip-core until is possible + * to process data. The idea is that we sleep for most of the time at the + * beginning because we are sure that the ip-core is not ready yet. + */ +static void ocores_poll_wait(struct ocores_i2c *i2c) +{ + int sleep_min = (8/i2c->bus_clock_khz) * 1000; /* us for 8bits */ + u8 loop_on; + + usleep_range(sleep_min, sleep_min + 10); + if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) + loop_on = OCI2C_STAT_BUSY; + else + loop_on = OCI2C_STAT_TIP; + while (oc_getreg(i2c, OCI2C_STATUS) & loop_on) + ; +} + + +/** + * It implements the polling logic + * @work: work instance descriptor + * + * Here we try to re-use as much as possible from the IRQ logic + */ +static void ocores_work(struct work_struct *work) +{ + struct ocores_i2c *i2c = container_of(work, + struct ocores_i2c, xfer_work); + irqreturn_t ret; + + do { + ocores_poll_wait(i2c); + ret = ocores_isr(-1, i2c); + } while (ret != IRQ_NONE); +} + static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) { struct ocores_i2c *i2c = i2c_get_adapdata(adap); @@ -245,6 +296,9 @@ static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) oc_setreg(i2c, OCI2C_DATA, i2c_8bit_addr_from_msg(i2c->msg)); oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START); + if (i2c->flags & OCORES_FLAG_POLL) + schedule_work(&i2c->xfer_work); + if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) || (i2c->state == STATE_DONE), HZ)) { return (i2c->state == STATE_DONE) ? num : -EIO; @@ -264,7 +318,8 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c) u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL); /* make sure the device is disabled */ - oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); + ctrl &= ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN); + oc_setreg(i2c, OCI2C_CONTROL, ctrl); prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1; prescale = clamp(prescale, 0, 0xffff); @@ -277,12 +332,16 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c) return -EINVAL; } + oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff); oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8); /* Init the device */ oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK); - oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN); + ctrl |= OCI2C_CTRL_EN; + if (i2c->flags != OCORES_FLAG_POLL) + ctrl |= OCI2C_CTRL_IEN; + oc_setreg(i2c, OCI2C_CONTROL, ctrl); return 0; } @@ -439,10 +498,6 @@ static int ocores_i2c_probe(struct platform_device *pdev) int ret; int i; - irq = platform_get_irq(pdev, 0); - if (irq < 0) - return irq; - i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL); if (!i2c) return -ENOMEM; @@ -497,18 +552,25 @@ static int ocores_i2c_probe(struct platform_device *pdev) } } + init_waitqueue_head(&i2c->wait); + + irq = platform_get_irq(pdev, 0); + if (irq == -ENXIO) { + i2c->flags |= OCORES_FLAG_POLL; + INIT_WORK(&i2c->xfer_work, ocores_work); + } else { + ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0, + pdev->name, i2c); + if (ret) { + dev_err(&pdev->dev, "Cannot claim IRQ\n"); + goto err_clk; + } + } + ret = ocores_init(&pdev->dev, i2c); if (ret) goto err_clk; - init_waitqueue_head(&i2c->wait); - ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0, - pdev->name, i2c); - if (ret) { - dev_err(&pdev->dev, "Cannot claim IRQ\n"); - goto err_clk; - } - /* hook up driver to tree */ platform_set_drvdata(pdev, i2c); i2c->adap = ocores_adapter; @@ -538,6 +600,8 @@ static int ocores_i2c_remove(struct platform_device *pdev) { struct ocores_i2c *i2c = platform_get_drvdata(pdev); + flush_scheduled_work(); + /* disable i2c logic */ oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL) & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN)); -- 2.15.0
