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Date: Fri, 15 Mar 2019 13:47:18 +0100
From: Simon Horman <horms@...ge.net.au>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc: linux-i2c@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
Keerthy <j-keerthy@...com>, Peter Rosin <peda@...ntia.se>,
Tony Lindgren <tony@...mide.com>,
Russell King <linux@...linux.org.uk>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Stefan Lengfeld <contact@...fanchrist.eu>,
Phil Reid <preid@...ctromag.com.au>,
Tero Kristo <t-kristo@...com>, linux-omap@...r.kernel.org,
linux-tegra@...r.kernel.org
Subject: Re: [RFC PATCH v2 5/7] i2c: busses: omap: Add the
master_xfer_irqless hook
On Sat, Mar 02, 2019 at 02:47:33PM +0100, Wolfram Sang wrote:
> From: Tero Kristo <t-kristo@...com>
>
> Add the master_xfer_irqless hook to enable i2c transactions
> in irq disabled contexts like the poweroff case.
>
> Signed-off-by: Tero Kristo <t-kristo@...com>
> Signed-off-by: Keerthy <j-keerthy@...com>
> Signed-off-by: Wolfram Sang <wsa+renesas@...g-engineering.com>
Minor nit below not withstanding
Reviewed-by: Simon Horman <horms+renesas@...ge.net.au>
> ---
> drivers/i2c/busses/i2c-omap.c | 79 ++++++++++++++++++++++++++++++++++++-------
> 1 file changed, 66 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index cd9c65f3d404..bf48126faf94 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -269,6 +269,8 @@ static const u8 reg_map_ip_v2[] = {
> [OMAP_I2C_IP_V2_IRQENABLE_CLR] = 0x30,
> };
>
> +static int omap_i2c_xfer_data(struct omap_i2c_dev *omap);
> +
> static inline void omap_i2c_write_reg(struct omap_i2c_dev *omap,
> int reg, u16 val)
> {
> @@ -648,15 +650,28 @@ static void omap_i2c_resize_fifo(struct omap_i2c_dev *omap, u8 size, bool is_rx)
> (1000 * omap->speed / 8);
> }
>
> +static void omap_i2c_wait(struct omap_i2c_dev *omap)
> +{
> + u16 stat;
> + u16 mask = omap_i2c_read_reg(omap, OMAP_I2C_IE_REG);
> + int count = 0;
> +
> + do {
> + stat = omap_i2c_read_reg(omap, OMAP_I2C_STAT_REG);
> + count++;
> + } while (!(stat & mask) && count < 5);
> +}
> +
> /*
> * Low level master read/write transaction.
> */
> static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
> - struct i2c_msg *msg, int stop)
> + struct i2c_msg *msg, int stop, bool polling)
> {
> struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
> unsigned long timeout;
> u16 w;
> + int ret;
>
> dev_dbg(omap->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
> msg->addr, msg->len, msg->flags, stop);
> @@ -680,7 +695,8 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
> w |= OMAP_I2C_BUF_RXFIF_CLR | OMAP_I2C_BUF_TXFIF_CLR;
> omap_i2c_write_reg(omap, OMAP_I2C_BUF_REG, w);
>
> - reinit_completion(&omap->cmd_complete);
> + if (!polling)
> + reinit_completion(&omap->cmd_complete);
> omap->cmd_err = 0;
>
> w = OMAP_I2C_CON_EN | OMAP_I2C_CON_MST | OMAP_I2C_CON_STT;
> @@ -732,8 +748,21 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
> * REVISIT: We should abort the transfer on signals, but the bus goes
> * into arbitration and we're currently unable to recover from it.
> */
> - timeout = wait_for_completion_timeout(&omap->cmd_complete,
> - OMAP_I2C_TIMEOUT);
> + if (!polling) {
> + timeout = wait_for_completion_timeout(&omap->cmd_complete,
> + OMAP_I2C_TIMEOUT);
> + } else {
> + do {
> + omap_i2c_wait(omap);
> + ret = omap_i2c_xfer_data(omap);
> + } while (ret == -EAGAIN);
> +
> + if (!ret)
> + timeout = 1;
> + else
> + timeout = 0;
nit: the following might be cleaner
ret = !!timeout;
> + }
> +
> if (timeout == 0) {
> dev_err(omap->dev, "controller timed out\n");
> omap_i2c_reset(omap);
> @@ -772,7 +801,8 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
> * to do the work during IRQ processing.
> */
> static int
> -omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> +omap_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg msgs[], int num,
> + bool polling)
> {
> struct omap_i2c_dev *omap = i2c_get_adapdata(adap);
> int i;
> @@ -794,7 +824,8 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> omap->set_mpu_wkup_lat(omap->dev, omap->latency);
>
> for (i = 0; i < num; i++) {
> - r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)));
> + r = omap_i2c_xfer_msg(adap, &msgs[i], (i == (num - 1)),
> + polling);
> if (r != 0)
> break;
> }
> @@ -813,6 +844,18 @@ omap_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> return r;
> }
>
> +static int
> +omap_i2c_xfer_irq(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> +{
> + return omap_i2c_xfer_common(adap, msgs, num, false);
> +}
> +
> +static int
> +omap_i2c_xfer_polling(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
> +{
> + return omap_i2c_xfer_common(adap, msgs, num, true);
> +}
> +
> static u32
> omap_i2c_func(struct i2c_adapter *adap)
> {
> @@ -1035,10 +1078,8 @@ omap_i2c_isr(int irq, void *dev_id)
> return ret;
> }
>
> -static irqreturn_t
> -omap_i2c_isr_thread(int this_irq, void *dev_id)
> +static int omap_i2c_xfer_data(struct omap_i2c_dev *omap)
> {
> - struct omap_i2c_dev *omap = dev_id;
> u16 bits;
> u16 stat;
> int err = 0, count = 0;
> @@ -1056,7 +1097,8 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
>
> if (!stat) {
> /* my work here is done */
> - goto out;
> + err = -EAGAIN;
> + break;
> }
>
> dev_dbg(omap->dev, "IRQ (ISR = 0x%04x)\n", stat);
> @@ -1165,14 +1207,25 @@ omap_i2c_isr_thread(int this_irq, void *dev_id)
> }
> } while (stat);
>
> - omap_i2c_complete_cmd(omap, err);
> + return err;
> +}
> +
> +static irqreturn_t
> +omap_i2c_isr_thread(int this_irq, void *dev_id)
> +{
> + int ret;
> + struct omap_i2c_dev *omap = dev_id;
> +
> + ret = omap_i2c_xfer_data(omap);
> + if (ret != -EAGAIN)
> + omap_i2c_complete_cmd(omap, ret);
>
> -out:
> return IRQ_HANDLED;
> }
>
> static const struct i2c_algorithm omap_i2c_algo = {
> - .master_xfer = omap_i2c_xfer,
> + .master_xfer = omap_i2c_xfer_irq,
> + .master_xfer_atomic = omap_i2c_xfer_polling,
> .functionality = omap_i2c_func,
> };
>
> --
> 2.11.0
>
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