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Message-ID: <20260108115233.GE302752@google.com>
Date: Thu, 8 Jan 2026 11:52:33 +0000
From: Lee Jones <lee@...nel.org>
To: Matthias Schiffer <matthias.schiffer@...tq-group.com>
Cc: Andi Shyti <andi.shyti@...nel.org>, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org, linux@...tq-group.com
Subject: Re: [PATCH v4 2/4] mfd: tqmx86: refactor I2C setup
On Wed, 10 Dec 2025, Matthias Schiffer wrote:
> Preparation for supporting the second I2C controller, and detecting both
> ocores and machxo2 controllers.
>
> - Introduce tqmx86_detect_i2c1()
> - Avoid the confusing "soft" I2C controller term - just call it the
> ocores I2C
> - Define TQMX86_REG_I2C_DETECT relative to I2C base register
>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@...tq-group.com>
> ---
>
> v2: no changes
>
> v3: no changes
>
> v4:
> - Keep resource and mfd_cell definitions at the toplevel
> - The very generic tqmx86_detect_i2c() of the previous version is replaced with
> tqmx86_detect_i2c1(), so we don't need to pass so many arguments around
>
> drivers/mfd/tqmx86.c | 92 +++++++++++++++++++++++---------------------
> 1 file changed, 49 insertions(+), 43 deletions(-)
>
> diff --git a/drivers/mfd/tqmx86.c b/drivers/mfd/tqmx86.c
> index 1c2fe3f912389..6d304741f8989 100644
> --- a/drivers/mfd/tqmx86.c
> +++ b/drivers/mfd/tqmx86.c
> @@ -18,7 +18,7 @@
>
> #define TQMX86_IOBASE 0x180
> #define TQMX86_IOSIZE 0x20
> -#define TQMX86_IOBASE_I2C 0x1a0
> +#define TQMX86_IOBASE_I2C1 0x1a0
> #define TQMX86_IOSIZE_I2C 0xa
> #define TQMX86_IOBASE_WATCHDOG 0x18b
> #define TQMX86_IOSIZE_WATCHDOG 0x2
> @@ -56,8 +56,8 @@
> #define TQMX86_REG_IO_EXT_INT_GPIO_SHIFT 4
> #define TQMX86_REG_SAUC 0x17
>
> -#define TQMX86_REG_I2C_DETECT 0x1a7
> -#define TQMX86_REG_I2C_DETECT_SOFT 0xa5
> +#define TQMX86_REG_I2C_DETECT 0x7
> +#define TQMX86_REG_I2C_DETECT_OCORES 0xa5
>
> static uint gpio_irq;
> module_param(gpio_irq, uint, 0);
> @@ -72,8 +72,8 @@ enum tqmx86_i2c1_resource_type {
> TQMX86_I2C1_IRQ,
> };
>
> -static struct resource tqmx_i2c_soft_resources[] = {
> - [TQMX86_I2C1_IO] = DEFINE_RES_IO(TQMX86_IOBASE_I2C, TQMX86_IOSIZE_I2C),
> +static struct resource tqmx_i2c1_resources[] = {
> + [TQMX86_I2C1_IO] = DEFINE_RES_IO(TQMX86_IOBASE_I2C1, TQMX86_IOSIZE_I2C),
> /* Placeholder for IRQ resource */
> [TQMX86_I2C1_IRQ] = {},
> };
> @@ -93,26 +93,24 @@ static struct resource tqmx_gpio_resources[] = {
> [TQMX86_GPIO_IRQ] = {},
> };
>
> -static struct i2c_board_info tqmx86_i2c_devices[] = {
> +static const struct i2c_board_info tqmx86_i2c1_devices[] = {
> {
> /* 4K EEPROM at 0x50 */
> I2C_BOARD_INFO("24c32", 0x50),
> },
> };
>
> -static struct ocores_i2c_platform_data ocores_platform_data = {
> - .num_devices = ARRAY_SIZE(tqmx86_i2c_devices),
> - .devices = tqmx86_i2c_devices,
> +static struct ocores_i2c_platform_data tqmx86_i2c1_platform_data_ocores = {
> + .num_devices = ARRAY_SIZE(tqmx86_i2c1_devices),
> + .devices = tqmx86_i2c1_devices,
> };
>
> -static const struct mfd_cell tqmx86_i2c_soft_dev[] = {
> - {
> - .name = "ocores-i2c",
> - .platform_data = &ocores_platform_data,
> - .pdata_size = sizeof(ocores_platform_data),
> - .resources = tqmx_i2c_soft_resources,
> - .num_resources = ARRAY_SIZE(tqmx_i2c_soft_resources),
> - },
> +static const struct mfd_cell tqmx86_i2c1_dev_ocores = {
> + .name = "ocores-i2c",
> + .platform_data = &tqmx86_i2c1_platform_data_ocores,
> + .pdata_size = sizeof(tqmx86_i2c1_platform_data_ocores),
> + .resources = tqmx_i2c1_resources,
> + .num_resources = ARRAY_SIZE(tqmx_i2c1_resources),
> };
>
> static const struct mfd_cell tqmx86_devs[] = {
> @@ -246,13 +244,40 @@ static int tqmx86_setup_irq(struct device *dev, const char *label, u8 irq,
> return 0;
> }
>
> +static int tqmx86_detect_i2c1(struct device *dev, void __iomem *io_base, int clock_khz)
> +{
> + u8 i2c_det;
> +
> + if (i2c1_irq) {
> + if (!tqmx86_setup_irq(dev, "I2C1", i2c1_irq, io_base,
It was better before.
Please place the return value into a local variable and compare that.
Function calls inside if () statements hurts readability.
> + TQMX86_REG_IO_EXT_INT_I2C1_SHIFT))
> + tqmx_i2c1_resources[TQMX86_I2C1_IRQ] = DEFINE_RES_IRQ(i2c1_irq);
> + }
> +
> + /*
> + * The I2C_DETECT register is in the range assigned to the I2C driver
> + * later, so we don't extend TQMX86_IOSIZE. Use inb() for this one-off
> + * access instead of ioport_map + unmap.
> + */
> + i2c_det = inb(TQMX86_IOBASE_I2C1 + TQMX86_REG_I2C_DETECT);
> +
> + if (i2c_det == TQMX86_REG_I2C_DETECT_OCORES) {
Reverse the logic and return early instead.
> + tqmx86_i2c1_platform_data_ocores.clock_khz = clock_khz;
> + return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> + &tqmx86_i2c1_dev_ocores, 1, NULL, 0,
> + NULL);
> + }
> +
> + return 0;
> +}
> +
> static int tqmx86_probe(struct platform_device *pdev)
> {
> - u8 board_id, sauc, rev, i2c_det;
> + u8 board_id, sauc, rev;
> struct device *dev = &pdev->dev;
> const char *board_name;
> void __iomem *io_base;
> - int err;
> + int err, clock_khz;
>
> io_base = devm_ioport_map(dev, TQMX86_IOBASE, TQMX86_IOSIZE);
> if (!io_base)
> @@ -267,13 +292,6 @@ static int tqmx86_probe(struct platform_device *pdev)
> "Found %s - Board ID %d, PCB Revision %d, PLD Revision %d\n",
> board_name, board_id, rev >> 4, rev & 0xf);
>
> - /*
> - * The I2C_DETECT register is in the range assigned to the I2C driver
> - * later, so we don't extend TQMX86_IOSIZE. Use inb() for this one-off
> - * access instead of ioport_map + unmap.
> - */
> - i2c_det = inb(TQMX86_REG_I2C_DETECT);
> -
> if (gpio_irq) {
> err = tqmx86_setup_irq(dev, "GPIO", gpio_irq, io_base,
> TQMX86_REG_IO_EXT_INT_GPIO_SHIFT);
> @@ -281,23 +299,11 @@ static int tqmx86_probe(struct platform_device *pdev)
> tqmx_gpio_resources[TQMX86_GPIO_IRQ] = DEFINE_RES_IRQ(gpio_irq);
> }
>
> - ocores_platform_data.clock_khz = tqmx86_board_id_to_clk_rate(dev, board_id);
> -
> - if (i2c_det == TQMX86_REG_I2C_DETECT_SOFT) {
> - if (i2c1_irq) {
> - err = tqmx86_setup_irq(dev, "I2C1", i2c1_irq, io_base,
> - TQMX86_REG_IO_EXT_INT_I2C1_SHIFT);
> - if (!err)
> - tqmx_i2c_soft_resources[TQMX86_I2C1_IRQ] = DEFINE_RES_IRQ(i2c1_irq);
> - }
> -
> - err = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> - tqmx86_i2c_soft_dev,
> - ARRAY_SIZE(tqmx86_i2c_soft_dev),
> - NULL, 0, NULL);
> - if (err)
> - return err;
> - }
> + clock_khz = tqmx86_board_id_to_clk_rate(dev, board_id);
Move this into the new functions and only call it if required.
> +
> + err = tqmx86_detect_i2c1(dev, io_base, clock_khz);
> + if (err)
> + return err;
>
> return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> tqmx86_devs,
> --
> TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany
> Amtsgericht München, HRB 105018
> Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider
> https://www.tq-group.com/
>
--
Lee Jones [李琼斯]
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