linux-kernel - Re: [PATCH v6 3/4] soc: ti: pruss: Add pruss_cfg_read()/update(), pruss_cfg_get_gpmux()/set

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Date:   Sat, 1 Apr 2023 16:07:19 +0200
From:   Simon Horman <simon.horman@...igine.com>
To:     MD Danish Anwar <danishanwar@...com>
Cc:     "Andrew F. Davis" <afd@...com>, Suman Anna <s-anna@...com>,
        Roger Quadros <rogerq@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        Tero Kristo <kristo@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        Nishanth Menon <nm@...com>, linux-remoteproc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, srk@...com, devicetree@...r.kernel.org,
        netdev@...r.kernel.org
Subject: Re: [PATCH v6 3/4] soc: ti: pruss: Add pruss_cfg_read()/update(),
 pruss_cfg_get_gpmux()/set_gpmux() APIs

On Fri, Mar 31, 2023 at 04:59:40PM +0530, MD Danish Anwar wrote:
> From: Suman Anna <s-anna@...com>
> 
> Add two new generic API pruss_cfg_read() and pruss_cfg_update() to
> the PRUSS platform driver to read and program respectively a register
> within the PRUSS CFG sub-module represented by a syscon driver. These
> APIs are internal to PRUSS driver.
> 
> Add two new helper functions pruss_cfg_get_gpmux() & pruss_cfg_set_gpmux()
> to get and set the GP MUX mode for programming the PRUSS internal wrapper
> mux functionality as needed by usecases.
> 
> Various useful registers and macros for certain register bit-fields and
> their values have also been added.
> 
> Signed-off-by: Suman Anna <s-anna@...com>
> Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
> Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@...aro.org>
> Signed-off-by: Puranjay Mohan <p-mohan@...com>
> Reviewed-by: Roger Quadros <rogerq@...nel.org>
> Reviewed-by: Tony Lindgren <tony@...mide.com>
> Signed-off-by: MD Danish Anwar <danishanwar@...com>

...

> diff --git a/drivers/soc/ti/pruss.h b/drivers/soc/ti/pruss.h
> new file mode 100644
> index 000000000000..4626d5f6b874
> --- /dev/null
> +++ b/drivers/soc/ti/pruss.h
> @@ -0,0 +1,112 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * PRU-ICSS Subsystem user interfaces
> + *
> + * Copyright (C) 2015-2023 Texas Instruments Incorporated - http://www.ti.com
> + *	MD Danish Anwar <danishanwar@...com>
> + */
> +
> +#ifndef _SOC_TI_PRUSS_H_
> +#define _SOC_TI_PRUSS_H_
> +
> +#include <linux/bits.h>
> +#include <linux/regmap.h>
> +
> +/*
> + * PRU_ICSS_CFG registers
> + * SYSCFG, ISRP, ISP, IESP, IECP, SCRP applicable on AMxxxx devices only
> + */
> +#define PRUSS_CFG_REVID         0x00
> +#define PRUSS_CFG_SYSCFG        0x04
> +#define PRUSS_CFG_GPCFG(x)      (0x08 + (x) * 4)
> +#define PRUSS_CFG_CGR           0x10
> +#define PRUSS_CFG_ISRP          0x14
> +#define PRUSS_CFG_ISP           0x18
> +#define PRUSS_CFG_IESP          0x1C
> +#define PRUSS_CFG_IECP          0x20
> +#define PRUSS_CFG_SCRP          0x24
> +#define PRUSS_CFG_PMAO          0x28
> +#define PRUSS_CFG_MII_RT        0x2C
> +#define PRUSS_CFG_IEPCLK        0x30
> +#define PRUSS_CFG_SPP           0x34
> +#define PRUSS_CFG_PIN_MX        0x40
> +
> +/* PRUSS_GPCFG register bits */
> +#define PRUSS_GPCFG_PRU_GPO_SH_SEL              BIT(25)
> +
> +#define PRUSS_GPCFG_PRU_DIV1_SHIFT              20
> +#define PRUSS_GPCFG_PRU_DIV1_MASK               GENMASK(24, 20)

There seems to be some redundancy in the encoding of '20' above.
I suspect this could be avoided by only defining ..._MASK
and using it with FIELD_SET() and FIELD_PREP().

> +
> +#define PRUSS_GPCFG_PRU_DIV0_SHIFT              15
> +#define PRUSS_GPCFG_PRU_DIV0_MASK               GENMASK(15, 19)

Perhaps this should be GENMASK(19, 15) ?

> +
> +#define PRUSS_GPCFG_PRU_GPO_MODE                BIT(14)
> +#define PRUSS_GPCFG_PRU_GPO_MODE_DIRECT         0
> +#define PRUSS_GPCFG_PRU_GPO_MODE_SERIAL         BIT(14)

Likewise, I suspect the awkwardness of using 0 to mean not BIT 14
could be avoided through use of FIELD_SET() and FIELD_PREP().
But maybe it doesn't help.

> +
> +#define PRUSS_GPCFG_PRU_GPI_SB                  BIT(13)
> +
> +#define PRUSS_GPCFG_PRU_GPI_DIV1_SHIFT          8
> +#define PRUSS_GPCFG_PRU_GPI_DIV1_MASK           GENMASK(12, 8)
> +
> +#define PRUSS_GPCFG_PRU_GPI_DIV0_SHIFT          3
> +#define PRUSS_GPCFG_PRU_GPI_DIV0_MASK           GENMASK(7, 3)
> +
> +#define PRUSS_GPCFG_PRU_GPI_CLK_MODE_POSITIVE   0
> +#define PRUSS_GPCFG_PRU_GPI_CLK_MODE_NEGATIVE   BIT(2)
> +#define PRUSS_GPCFG_PRU_GPI_CLK_MODE            BIT(2)
> +
> +#define PRUSS_GPCFG_PRU_GPI_MODE_MASK           GENMASK(1, 0)
> +#define PRUSS_GPCFG_PRU_GPI_MODE_SHIFT          0
> +
> +#define PRUSS_GPCFG_PRU_MUX_SEL_SHIFT           26
> +#define PRUSS_GPCFG_PRU_MUX_SEL_MASK            GENMASK(29, 26)
> +
> +/* PRUSS_MII_RT register bits */
> +#define PRUSS_MII_RT_EVENT_EN                   BIT(0)
> +
> +/* PRUSS_SPP register bits */
> +#define PRUSS_SPP_XFER_SHIFT_EN                 BIT(1)
> +#define PRUSS_SPP_PRU1_PAD_HP_EN                BIT(0)
> +#define PRUSS_SPP_RTU_XFR_SHIFT_EN              BIT(3)

...