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spi: rp2040-gpio-bridge: Fix fast_xfer with strict RP1 pinmux #7728

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spi: rp2040-gpio-bridge: Fix fast_xfer with strict RP1 pinmux #7728

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9cdbd5e
spi: rp2040-gpio-bridge: Don't request the shared fast_xfer data pin
jlab13 Oct 30, 2026
e879e42
spi: rp2040-gpio-bridge: Use of_property_present() for i2c lock flag
jlab13 Oct 30, 2026
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98 changes: 82 additions & 16 deletions drivers/spi/spi-rp2040-gpio-bridge.c
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,16 @@ static_assert(MD5_DIGEST_SIZE == MANIFEST_UNIT_SIZE);

#define NUM_GPIO 24

/* RP1 GPIO/RIO register layout, see pinctrl-rp1 */
#define RP1_RIO_OUT 0x00
#define RP1_RIO_OE 0x04
#define RP1_SET_OFFSET 0x2000
#define RP1_CLR_OFFSET 0x3000
#define RP1_GPIO_CTRL_FUNCSEL_MASK 0x0000001f
#define RP1_GPIO_CTRL_OUTOVER_MASK 0x00003000
#define RP1_GPIO_CTRL_OEOVER_MASK 0x0000c000
#define RP1_FSEL_GPIO 0x05

enum rp2040_gbdg_fixed_size_commands {
/* 10-byte commands */
CMD_SAVE_CACHE = 0x07,
Expand Down Expand Up @@ -114,8 +124,9 @@ struct rp2040_gbdg {
u32 gpio_requested;
u32 gpio_direction;

bool fast_xfer;
bool fast_xfer_requires_i2c_lock;
struct gpio_descs *fast_xfer_gpios;
struct gpio_desc *fast_xfer_clock_gpio;
u32 fast_xfer_recv_gpio_base;
u8 fast_xfer_data_index;
u8 fast_xfer_clock_index;
Expand Down Expand Up @@ -198,6 +209,44 @@ static int rp2040_gbdg_rp1_write_mux(struct rp2040_gbdg *priv_data, u8 gpio,
return 0;
}

/*
* Equivalent of gpiod_direction_output() for an RP1 pin, done through the
* registers directly. The fast_xfer data pin doubles as the I2C SDA line and
* is owned by the I2C controller through pinctrl, so it can't be requested
* from gpiolib while RP1 pinmux is strict. It is only driven with the I2C bus
* locked, and rp2040_gbdg_fast_xfer() restores the original mux afterwards.
* The pad is left as is: pinctrl-rp1 enables input and output on it for any
* muxed function.
*/
static int rp2040_gbdg_rp1_set_output(struct rp2040_gbdg *priv_data, u8 gpio,
int value)
{
size_t bank_offset;
u8 shift_offset;
u32 ctrl;
int ret;

ret = rp2040_gbdg_rp1_calc_offsets(gpio, &bank_offset, &shift_offset);
if (ret)
return ret;

writel(BIT(shift_offset),
priv_data->rio_base + bank_offset + RP1_RIO_OUT +
(value ? RP1_SET_OFFSET : RP1_CLR_OFFSET));
writel(BIT(shift_offset),
priv_data->rio_base + bank_offset + RP1_RIO_OE + RP1_SET_OFFSET);

ret = rp2040_gbdg_rp1_read_mux(priv_data, gpio, &ctrl);
if (ret)
return ret;

ctrl &= ~(RP1_GPIO_CTRL_FUNCSEL_MASK | RP1_GPIO_CTRL_OUTOVER_MASK |
RP1_GPIO_CTRL_OEOVER_MASK);
ctrl |= RP1_FSEL_GPIO;

return rp2040_gbdg_rp1_write_mux(priv_data, gpio, ctrl);
}

static size_t rp2040_gbdg_max_transfer_size(struct spi_device *spi)
{
return MAX_TRANSFER_SIZE;
Expand Down Expand Up @@ -402,7 +451,7 @@ static int rp2040_gbdg_set_remote_buffer_fast(struct rp2040_gbdg *priv_data,

if (len > RP2040_GBDG_BLOCK_SIZE)
return -EMSGSIZE;
if (!priv_data->fast_xfer_gpios)
if (!priv_data->fast_xfer)
return -EIO;

ret = rp2040_gbdg_10byte_cmd(client, CMD_DAT_RECV,
Expand Down Expand Up @@ -450,7 +499,7 @@ static int rp2040_gbdg_set_remote_buffer_i2c(struct rp2040_gbdg *priv_data,
static int rp2040_gbdg_set_remote_buffer(struct rp2040_gbdg *priv_data,
const u8 *data, unsigned int len)
{
if (priv_data->fast_xfer_gpios)
if (priv_data->fast_xfer)
return rp2040_gbdg_set_remote_buffer_fast(priv_data, data, len);
else
return rp2040_gbdg_set_remote_buffer_i2c(priv_data, data, len);
Expand Down Expand Up @@ -625,7 +674,7 @@ static int rp2040_gbdg_fast_xfer(struct rp2040_gbdg *priv_data, const u8 *data,
rp2040_gbdg_rp1_read_mux(priv_data, priv_data->fast_xfer_clock_index,
&clock_mux);

gpiod_direction_output(priv_data->fast_xfer_gpios->desc[0], 1);
rp2040_gbdg_rp1_set_output(priv_data, priv_data->fast_xfer_data_index, 1);

rp2040_gbdg_rp1_calc_offsets(priv_data->fast_xfer_data_index,
&data_bank, &data_offset);
Expand Down Expand Up @@ -671,7 +720,7 @@ static int rp2040_gbdg_transfer_bypass(struct rp2040_gbdg *priv_data,
int ret;
u8 *buf;

if (priv_data->fast_xfer_gpios) {
if (priv_data->fast_xfer) {
ret = rp2040_gbdg_10byte_cmd(
priv_data->client, CMD_DAT_EMIT,
priv_data->fast_xfer_recv_gpio_base, length);
Expand Down Expand Up @@ -927,6 +976,8 @@ static void rp2040_gbdg_parse_dt(struct rp2040_gbdg *rp2040_gbdg)
struct of_phandle_args of_args[2] = { 0 };
struct device *dev = &client->dev;
struct device_node *dn;
size_t bank_offset;
u8 shift_offset;

rp2040_gbdg->bypass_cache =
of_property_read_bool(client->dev.of_node, "bypass-cache");
Expand Down Expand Up @@ -963,26 +1014,37 @@ static void rp2040_gbdg_parse_dt(struct rp2040_gbdg *rp2040_gbdg)
goto node_put;
}

rp2040_gbdg->fast_xfer_gpios =
devm_gpiod_get_array_optional(dev, "fast_xfer", GPIOD_ASIS);
if (IS_ERR_OR_NULL(rp2040_gbdg->fast_xfer_gpios)) {
rp2040_gbdg->fast_xfer_gpios = NULL;
dev_info(dev, "Could not acquire fast_xfer-gpios\n");
/*
* Only the clock pin is requested from gpiolib. The data pin is shared
* with the I2C bus, see rp2040_gbdg_rp1_set_output().
*/
if (rp2040_gbdg_rp1_calc_offsets(of_args[0].args[0], &bank_offset,
&shift_offset)) {
dev_info(dev, "Invalid fast_xfer data gpio %u\n",
of_args[0].args[0]);
goto node_put;
}

rp2040_gbdg->fast_xfer_clock_gpio =
devm_gpiod_get_index(dev, "fast_xfer", 1, GPIOD_ASIS);
if (IS_ERR(rp2040_gbdg->fast_xfer_clock_gpio)) {
rp2040_gbdg->fast_xfer_clock_gpio = NULL;
dev_info(dev, "Could not acquire fast_xfer clock gpio\n");
goto node_put;
}

rp2040_gbdg->fast_xfer_data_index = of_args[0].args[0];
rp2040_gbdg->fast_xfer_clock_index = of_args[1].args[0];
rp2040_gbdg->fast_xfer_requires_i2c_lock = of_property_read_bool(
rp2040_gbdg->fast_xfer_requires_i2c_lock = of_property_present(
client->dev.of_node, "fast_xfer_requires_i2c_lock");

rp2040_gbdg->gpio_base = of_iomap(dn, 0);
if (IS_ERR_OR_NULL(rp2040_gbdg->gpio_base)) {
dev_info(&client->dev, "%s() unable to map gpio_base\n",
__func__);
rp2040_gbdg->gpio_base = NULL;
devm_gpiod_put_array(dev, rp2040_gbdg->fast_xfer_gpios);
rp2040_gbdg->fast_xfer_gpios = NULL;
devm_gpiod_put(dev, rp2040_gbdg->fast_xfer_clock_gpio);
rp2040_gbdg->fast_xfer_clock_gpio = NULL;
goto node_put;
}

Expand All @@ -993,16 +1055,20 @@ static void rp2040_gbdg_parse_dt(struct rp2040_gbdg *rp2040_gbdg)
rp2040_gbdg->rio_base = NULL;
iounmap(rp2040_gbdg->gpio_base);
rp2040_gbdg->gpio_base = NULL;
devm_gpiod_put_array(dev, rp2040_gbdg->fast_xfer_gpios);
rp2040_gbdg->fast_xfer_gpios = NULL;
devm_gpiod_put(dev, rp2040_gbdg->fast_xfer_clock_gpio);
rp2040_gbdg->fast_xfer_clock_gpio = NULL;
goto node_put;
}

/*
* fast_xfer mode requires first data bit to be clocked on a rising
* edge. Configure as output-low here before fast_xfer mode is entered.
*/
gpiod_direction_output(rp2040_gbdg->fast_xfer_gpios->desc[1], 0);
gpiod_direction_output(rp2040_gbdg->fast_xfer_clock_gpio, 0);
rp2040_gbdg->fast_xfer = true;
dev_info(dev, "fast_xfer enabled (data gpio %u, clock gpio %u)\n",
rp2040_gbdg->fast_xfer_data_index,
rp2040_gbdg->fast_xfer_clock_index);
node_put:
if (of_args[0].np)
of_node_put(of_args[0].np);
Expand Down