On 2017-01-09 10:02, Phil Reid wrote:
> Various muxes can aggregate multiple interrupts from each i2c bus.
> All of the muxes with interrupt support combine the active low irq lines
> using an internal 'and' function and generate a combined active low
> output. The muxes do provide the ability to read a control register to
> determine which irq is active. By making the mux an irq controller isr
> latency can potentially be reduced by reading the status register and
> then only calling the registered isr on that bus segment.
>
> As there is no irq masking on the mux irq are disabled until irq_unmask is
> called at least once.
>
I had a second reading of this patch. I'm still no master-of-irqs, though.
Anyway, I have some questions below. I guess it mostly shows that I don't
really know what I'm talking about here...
> Signed-off-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx>
> ---
> drivers/i2c/muxes/i2c-mux-pca954x.c | 127 +++++++++++++++++++++++++++++++++++-
> 1 file changed, 125 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index bbf088e..84fc767 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -41,14 +41,19 @@
> #include <linux/i2c.h>
> #include <linux/i2c-mux.h>
> #include <linux/i2c/pca954x.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_device.h>
> +#include <linux/of_irq.h>
> #include <linux/pm.h>
> #include <linux/slab.h>
>
> #define PCA954X_MAX_NCHANS 8
>
> +#define PCA954X_IRQ_OFFSET 4
> +
> enum pca_type {
> pca_9540,
> pca_9542,
> @@ -63,6 +68,7 @@ enum pca_type {
> struct chip_desc {
> u8 nchans;
> u8 enable; /* used for muxes only */
> + u8 has_irq;
> enum muxtype {
> pca954x_ismux = 0,
> pca954x_isswi
> @@ -75,6 +81,9 @@ struct pca954x {
> u8 last_chan; /* last register value */
> u8 deselect;
> struct i2c_client *client;
> +
> + struct irq_domain *irq;
> + unsigned int irq_mask;
> };
>
> /* Provide specs for the PCA954x types we know about */
> @@ -87,19 +96,23 @@ struct pca954x {
> [pca_9542] = {
> .nchans = 2,
> .enable = 0x4,
> + .has_irq = 1,
> .muxtype = pca954x_ismux,
> },
> [pca_9543] = {
> .nchans = 2,
> + .has_irq = 1,
> .muxtype = pca954x_isswi,
> },
> [pca_9544] = {
> .nchans = 4,
> .enable = 0x4,
> + .has_irq = 1,
> .muxtype = pca954x_ismux,
> },
> [pca_9545] = {
> .nchans = 4,
> + .has_irq = 1,
> .muxtype = pca954x_isswi,
> },
> [pca_9547] = {
> @@ -222,6 +235,102 @@ static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
> return pca954x_reg_write(muxc->parent, client, data->last_chan);
> }
>
> +static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
> +{
> + struct pca954x *data = dev_id;
> + unsigned int child_irq;
> + int ret, i, handled;
> +
> + ret = i2c_smbus_read_byte(data->client);
> + if (ret < 0)
> + return IRQ_NONE;
> +
> + for (i = 0; i < data->chip->nchans; i++) {
> + if (ret & BIT(PCA954X_IRQ_OFFSET + i)) {
> + child_irq = irq_linear_revmap(data->irq, i);
> + handle_nested_irq(child_irq);
> + handled++;
> + }
> + }
> + return handled ? IRQ_HANDLED : IRQ_NONE;
> +}
> +
> +static void pca954x_irq_mask(struct irq_data *idata)
> +{
> + struct pca954x *data = irq_data_get_irq_chip_data(idata);
> + unsigned int pos = idata->hwirq;
> +
> + data->irq_mask &= ~BIT(pos);
> + if (!data->irq_mask)
> + disable_irq(data->client->irq);
> +}
> +
> +static void pca954x_irq_unmask(struct irq_data *idata)
> +{
> + struct pca954x *data = irq_data_get_irq_chip_data(idata);
> + unsigned int pos = idata->hwirq;
> +
> + if (!data->irq_mask)
> + enable_irq(data->client->irq);
> + data->irq_mask |= BIT(pos);
> +}
I assume the irq core makes sure that .irq_mask and .irq_unmask may not
be called concurrently?
> +
> +static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
> +{
> + if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
> + return -EINVAL;
> + return 0;
> +}
> +
> +static struct irq_chip pca954x_irq_chip = {
> + .name = "i2c-mux-pca954x",
> + .irq_mask = pca954x_irq_mask,
> + .irq_unmask = pca954x_irq_unmask,
> + .irq_set_type = pca954x_irq_set_type,
> +};
> +
> +static int pca954x_irq_setup(struct i2c_mux_core *muxc)
> +{
> + struct pca954x *data = i2c_mux_priv(muxc);
> + struct i2c_client *client = data->client;
> + int c, err, irq;
> +
> + if (!data->chip->has_irq || client->irq <= 0)
> + return 0;
I assume "client->irq <= 0" means that users not specifying any interrupts
continue to behave as they use to, right?
BTW, what does client->irq == 0 represent?
Cheers,
peda
> +
> + data->irq = irq_domain_add_linear(client->dev.of_node,
> + data->chip->nchans,
> + &irq_domain_simple_ops, data);
> + if (!data->irq)
> + return -ENODEV;
> +
> + for (c = 0; c < data->chip->nchans; c++) {
> + irq = irq_create_mapping(data->irq, c);
> + irq_set_chip_data(irq, data);
> + irq_set_chip_and_handler(irq, &pca954x_irq_chip,
> + handle_simple_irq);
> + }
> +
> + err = devm_request_threaded_irq(&client->dev, data->client->irq, NULL,
> + pca954x_irq_handler,
> + IRQF_ONESHOT | IRQF_SHARED,
> + "pca954x", data);
> + if (err)
> + goto err_req_irq;
> +
> + disable_irq(data->client->irq);
> +
> + return 0;
> +err_req_irq:
> + for (c = 0; c < data->chip->nchans; c++) {
> + irq = irq_find_mapping(data->irq, c);
> + irq_dispose_mapping(irq);
> + }
> + irq_domain_remove(data->irq);
> +
> + return err;
> +}
> +
> /*
> * I2C init/probing/exit functions
> */
> @@ -286,6 +395,10 @@ static int pca954x_probe(struct i2c_client *client,
> idle_disconnect_dt = of_node &&
> of_property_read_bool(of_node, "i2c-mux-idle-disconnect");
>
> + ret = pca954x_irq_setup(muxc);
> + if (ret)
> + goto fail_del_adapters;
> +
> /* Now create an adapter for each channel */
> for (num = 0; num < data->chip->nchans; num++) {
> bool idle_disconnect_pd = false;
> @@ -311,7 +424,7 @@ static int pca954x_probe(struct i2c_client *client,
> dev_err(&client->dev,
> "failed to register multiplexed adapter"
> " %d as bus %d\n", num, force);
> - goto virt_reg_failed;
> + goto fail_del_adapters;
> }
> }
>
> @@ -322,7 +435,7 @@ static int pca954x_probe(struct i2c_client *client,
>
> return 0;
>
> -virt_reg_failed:
> +fail_del_adapters:
> i2c_mux_del_adapters(muxc);
> return ret;
> }
> @@ -330,6 +443,16 @@ static int pca954x_probe(struct i2c_client *client,
> static int pca954x_remove(struct i2c_client *client)
> {
> struct i2c_mux_core *muxc = i2c_get_clientdata(client);
> + struct pca954x *data = i2c_mux_priv(muxc);
> + int c, irq;
> +
> + if (data->irq) {
> + for (c = 0; c < data->chip->nchans; c++) {
> + irq = irq_find_mapping(data->irq, c);
> + irq_dispose_mapping(irq);
> + }
> + irq_domain_remove(data->irq);
> + }
>
> i2c_mux_del_adapters(muxc);
> return 0;
>
--
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