Re: [PATCH v3 35/47] mfd: ti_am335x_tscadc: Add ADC1/magnetic reader support

[Miquel Raynal <miquel.raynal@bootlin.com>]

Hi Lee,

lee.jones@linaro.org wrote on Wed, 22 Sep 2021 17:00:20 +0100:

> On Wed, 15 Sep 2021, Miquel Raynal wrote:
> 
> > Introduce a new compatible that has another set of driver data,
> > targeting am437x SoCs with a magnetic reader instead of the
> > touchscreen and a more featureful set of registers.
> > 
> > Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
> > Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > ---
> >  drivers/mfd/ti_am335x_tscadc.c       | 41 ++++++++++++++++++++++++----
> >  include/linux/mfd/ti_am335x_tscadc.h |  7 +++++
> >  2 files changed, 42 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/mfd/ti_am335x_tscadc.c b/drivers/mfd/ti_am335x_tscadc.c
> > index 65c0fa735a71..155a8ed879b3 100644
> > --- a/drivers/mfd/ti_am335x_tscadc.c
> > +++ b/drivers/mfd/ti_am335x_tscadc.c
> > @@ -121,11 +121,11 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >  	struct mfd_cell *cell;
> >  	struct property *prop;
> >  	const __be32 *cur;
> > -	bool use_tsc = false;
> > +	bool use_tsc = false, use_mag = false;
> >  	u32 val;
> >  	int err;
> >  	int tscmag_wires = 0, adc_channels = 0, cell_idx = 0, total_channels;
> > -	int readouts = 0;
> > +	int readouts = 0, mag_tracks = 0;
> >  
> >  	/* Allocate memory for device */
> >  	tscadc = devm_kzalloc(&pdev->dev, sizeof(*tscadc), GFP_KERNEL);
> > @@ -148,6 +148,16 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >  		of_node_put(node);
> >  		if (tscmag_wires)
> >  			use_tsc = true;
> > +	} else {
> > +		/*
> > +		 * When adding support for the magnetic reader, here is the
> > +		 * place to look for the number of tracks used from device tree.
> > +		 * Let's default to 0 for now.
> > +		 */
> > +		mag_tracks = 0;
> > +		tscmag_wires = mag_tracks * 2;
> > +		if (tscmag_wires)
> > +			use_mag = true;
> >  	}
> >  
> >  	node = of_get_child_by_name(pdev->dev.of_node, "adc");
> > @@ -209,8 +219,9 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >  	 * The TSC_ADC_Subsystem has 2 clock domains: OCP_CLK and ADC_CLK.
> >  	 * ADCs produce a 12-bit sample every 15 ADC_CLK cycles.
> >  	 * am33xx ADCs expect to capture 200ksps.
> > -	 * We need the ADC clocks to run at 3MHz.
> > -	 * This frequency is valid since TSC_ADC_SS controller design
> > +	 * am47xx ADCs expect to capture 867ksps.
> > +	 * We need ADC clocks respectively running at 3MHz and 13MHz.
> > +	 * These frequencies are valid since TSC_ADC_SS controller design
> >  	 * assumes the OCP clock is at least 6x faster than the ADC clock.
> >  	 */
> >  	clk = devm_clk_get(&pdev->dev, NULL);
> > @@ -238,6 +249,9 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >  			else
> >  				tscadc->ctrl |= CNTRLREG_TSC_4WIRE;
> >  		}
> > +	} else {
> > +		tscadc->ctrl |= CNTRLREG_MAG_PREAMP_PWRDOWN |
> > +				CNTRLREG_MAG_PREAMP_BYPASS;
> >  	}
> >  	regmap_write(tscadc->regmap, REG_CTRL, tscadc->ctrl);
> >  
> > @@ -246,7 +260,7 @@ static	int ti_tscadc_probe(struct platform_device *pdev)
> >  	/* Enable the TSC module enable bit */
> >  	regmap_write(tscadc->regmap, REG_CTRL, tscadc->ctrl | CNTRLREG_SSENB);
> >  
> > -	/* TSC Cell */
> > +	/* TSC or MAG Cell */
> >  	if (tscmag_wires > 0) {
> >  		cell = &tscadc->cells[cell_idx++];
> >  		cell->name = tscadc->data->name_tscmag;
> > @@ -334,6 +348,7 @@ static SIMPLE_DEV_PM_OPS(tscadc_pm_ops, tscadc_suspend, tscadc_resume);
> >  
> >  static const struct ti_tscadc_data tscdata = {
> >  	.has_tsc = true,
> > +	.has_mag = false,
> >  	.name_tscmag = "TI-am335x-tsc",
> >  	.compat_tscmag = "ti,am3359-tsc",
> >  	.name_adc = "TI-am335x-adc",
> > @@ -341,11 +356,25 @@ static const struct ti_tscadc_data tscdata = {
> >  	.target_clk_rate = TSC_ADC_CLK,
> >  };
> >  
> > +static const struct ti_tscadc_data magdata = {
> > +	.has_tsc = false,
> > +	.has_mag = true,  
> 
> Why 2 bools?
> 
> Better to have a single u8:
> 
>   MODE_TOUCHSCREEN
>   MODE_MAG_STRING
>   MODE_NONE

It's not a mode like "please use this feature", it is more like a
feature that is present and we need to know which one it is.

Anyway, I can use an enum for this, fine.

> 
> > +	.name_tscmag = "TI-am43xx-mag",
> > +	.compat_tscmag = "ti,am4372-mag",
> > +	.name_adc = "TI-am43xx-adc",
> > +	.compat_adc = "ti,am4372-adc",
> > +	.target_clk_rate = MAG_ADC_CLK,
> > +};
> > +
> >  static const struct of_device_id ti_tscadc_dt_ids[] = {
> >  	{
> >  		.compatible = "ti,am3359-tscadc",
> >  		.data = &tscdata,
> >  	},
> > +	{
> > +		.compatible = "ti,am4372-magadc",
> > +		.data = &magdata,
> > +	},
> >  	{ }
> >  };
> >  MODULE_DEVICE_TABLE(of, ti_tscadc_dt_ids);
> > @@ -363,6 +392,6 @@ static struct platform_driver ti_tscadc_driver = {
> >  
> >  module_platform_driver(ti_tscadc_driver);
> >  
> > -MODULE_DESCRIPTION("TI touchscreen / ADC MFD controller driver");
> > +MODULE_DESCRIPTION("TI touchscreen/magnetic reader/ADC MFD controller driver");  
> 
> Magnetic what?  Tape, disk, stripe?

I guess my current knowledge of English tricked me as I thought
"magnetic reader" was clear enough for everybody, but I'll make the
commit logs and this module description clearer by specifying the
"stripe" keyword, sure.
 
> 
> >  MODULE_AUTHOR("Rachna Patil <rachna@ti.com>");
> >  MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> > index 467b3bec4335..9a412e6d764b 100644
> > --- a/include/linux/mfd/ti_am335x_tscadc.h
> > +++ b/include/linux/mfd/ti_am335x_tscadc.h
> > @@ -106,6 +106,11 @@
> >  #define CNTRLREG_TSC_8WIRE	CNTRLREG_TSC_AFE_CTRL(3)
> >  #define CNTRLREG_TSC_ENB	BIT(7)
> >  
> > +/*Control registers bitfields  for MAGADC IP */
> > +#define CNTRLREG_MAGADCENB      BIT(0)
> > +#define CNTRLREG_MAG_PREAMP_PWRDOWN BIT(5)
> > +#define CNTRLREG_MAG_PREAMP_BYPASS  BIT(6)
> > +
> >  /* FIFO READ Register */
> >  #define FIFOREAD_DATA_MASK	GENMASK(11, 0)
> >  #define FIFOREAD_CHNLID_MASK	GENMASK(19, 16)
> > @@ -119,6 +124,7 @@
> >  #define CHARGE_STEP		0x11
> >  
> >  #define TSC_ADC_CLK		(3 * HZ_PER_MHZ)
> > +#define MAG_ADC_CLK		(13 * HZ_PER_MHZ)
> >  #define TOTAL_STEPS		16
> >  #define TOTAL_CHANNELS		8
> >  #define FIFO1_THRESHOLD		19
> > @@ -141,6 +147,7 @@
> >  
> >  struct ti_tscadc_data {
> >  	bool has_tsc;
> > +	bool has_mag;
> >  	char *name_tscmag;
> >  	char *compat_tscmag;
> >  	char *name_adc;  
> 


Thanks,
Miquèl