Re: [PATCH v5 3/5] i2c: mux: pca954x: Add interrupt controller support

[Peter Rosin <peda@axentia.se>]

On 2017-01-17 09:00, 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.
> 
> Signed-off-by: Phil Reid <preid@electromag.com.au>

Acked-by: Peter Rosin <peda@axentia.se>

Cheers,
peda

> ---
>  drivers/i2c/muxes/i2c-mux-pca954x.c | 141 +++++++++++++++++++++++++++++++++++-
>  1 file changed, 139 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/muxes/i2c-mux-pca954x.c b/drivers/i2c/muxes/i2c-mux-pca954x.c
> index bbf088e..f55da88 100644
> --- a/drivers/i2c/muxes/i2c-mux-pca954x.c
> +++ b/drivers/i2c/muxes/i2c-mux-pca954x.c
> @@ -41,14 +41,20 @@
>  #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>
> +#include <linux/spinlock.h>
>  
>  #define PCA954X_MAX_NCHANS 8
>  
> +#define PCA954X_IRQ_OFFSET 4
> +
>  enum pca_type {
>  	pca_9540,
>  	pca_9542,
> @@ -63,6 +69,7 @@ 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 +82,10 @@ struct pca954x {
>  	u8 last_chan;		/* last register value */
>  	u8 deselect;
>  	struct i2c_client *client;
> +
> +	struct irq_domain *irq;
> +	unsigned int irq_mask;
> +	spinlock_t lock;
>  };
>  
>  /* Provide specs for the PCA954x types we know about */
> @@ -87,19 +98,23 @@ 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 +237,114 @@ 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;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	data->irq_mask &= ~BIT(pos);
> +	if (!data->irq_mask)
> +		disable_irq(data->client->irq);
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +}
> +
> +static void pca954x_irq_unmask(struct irq_data *idata)
> +{
> +	struct pca954x *data = irq_data_get_irq_chip_data(idata);
> +	unsigned int pos = idata->hwirq;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&data->lock, flags);
> +
> +	if (!data->irq_mask)
> +		enable_irq(data->client->irq);
> +	data->irq_mask |= BIT(pos);
> +
> +	spin_unlock_irqrestore(&data->lock, flags);
> +}
> +
> +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;
> +
> +	spin_lock_init(&data->lock);
> +
> +	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 +409,10 @@ 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 +438,7 @@ 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 +449,7 @@ 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 +457,16 @@ 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;
>