drivers/i2c/sx9324: Add support for Linux's SX9324 driver

SX9324 driver is updated per Linux's documentation found at
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/devicetree/bindings/iio/proximity/semtech,sx9324.yaml

Supporting logic for the deprecated SX932x driver is hence guarded by
DRIVERS_I2C_SX9324_SUPPORT_LEGACY_LINUX_DRIVER

This patch by itself does not introduce functional changes to any board.
The legacy SX932x Linux driver never reached upstream Linux and is only
available in ChromeOS kernel fork of 4.4 and 5.4. Linux later accepted
a different implementation named SX9324 and has been available since
5.4. Ideally all variants should adopt the new driver; however, during
the transition phase, coreboot must support both drivers. It is better
to have a single firmware build that can work with both Linux kernel
drivers by specifying both sets of properties. Legacy driver support
should be deleted once all variants finish migration.

BUG=b:242662878
TEST=Dump ACPI SSDT then verify _DSD entries related to the legacy
     SX932x driver are identical w/ and w/o this patch
     (Tested on Craask and Nivviks)

Change-Id: I42cd6841c3a270c242ed2e739db245e858eadb3b
Signed-off-by: Victor Ding <victording@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69192
Reviewed-by: Reka Norman <rekanorman@chromium.org>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Eric Lai <eric_lai@quanta.corp-partner.google.com>

4 files changed, 177 insertions, 0 deletions

diff --git a/src/drivers/i2c/sx9324/Kconfig b/src/drivers/i2c/sx9324/Kconfig
index 77f6967b7e6b..222ff8d4763a 100644
--- a/src/drivers/i2c/sx9324/Kconfig
+++ b/src/drivers/i2c/sx9324/Kconfig
@@ -4,3 +4,19 @@ config DRIVERS_I2C_SX9324
 	depends on HAVE_ACPI_TABLES
 	help
 	  Board has a Semtech SX9324 proximity sensor.
+
+config DRIVERS_I2C_SX9324_SUPPORT_LEGACY_LINUX_DRIVER
+	bool
+	default n
+	depends on DRIVERS_I2C_SX9324
+	help
+	  Board may use the legacy sx932x linux driver.
+	  This option is mainly to ease migrating from the legacy driver to the
+	  Linux one and should be deleted once all variants finish migration.
+	  This driver never reached upstream Linux and is only available in
+	  ChromeOS kernel fork of 4.4 and 5.4. Linux later accepted a different
+	  implementation named SX9324 and has been available since 5.4.
+	  Ideally all variants should adopt the new driver; however, during the
+	  transition phase, coreboot must support both drivers. By selecting this
+	  option, coreboot's SX9324 driver will specify all properties to work with
+	  both Linux kernel drivers.
diff --git a/src/drivers/i2c/sx9324/chip.h b/src/drivers/i2c/sx9324/chip.h
index 9c9dd3cf3579..47910fb7a02c 100644
--- a/src/drivers/i2c/sx9324/chip.h
+++ b/src/drivers/i2c/sx9324/chip.h
@@ -23,7 +23,148 @@ struct drivers_i2c_sx9324_config {
 
 	/* IO-APIC interrupt */
 	struct acpi_irq irq;
+
+	/*
+	semtech,ph0-pin:
+	  description: |
+	    Array of 3 entries. Index represent the id of the CS pin.
+	    Value indicates how each CS pin is used during phase 0.
+	    Each of the 3 pins have the following value -
+	    0 : unused (high impedance)
+	    1 : measured input
+	    2 : dynamic shield
+	    3 : grounded.
+	    For instance, CS0 measured, CS1 shield and CS2 ground is [1, 2, 3]
+	  items:
+	    enum: [ 0, 1, 2, 3 ]
+	  minItems: 3
+	  maxItems: 3
+	*/
+	uint64_t ph0_pin[3];
+
+	/*
+	semtech,ph1-pin:
+	  Same as ph0-pin for phase 1.
+	*/
+	uint64_t ph1_pin[3];
+
+	/*
+	semtech,ph2-pin:
+	  Same as ph0-pin for phase 2.
+	*/
+	uint64_t ph2_pin[3];
+
+	/*
+	semtech,ph3-pin:
+	  Same as ph0-pin for phase 3.
+	*/
+	uint64_t ph3_pin[3];
+
+	/*
+	semtech,ph01-resolution:
+	  enum: [8, 16, 32, 64, 128, 256, 512, 1024]
+	  description:
+	    Capacitance measurement resolution. For phase 0 and 1.
+	    Higher the number, higher the resolution.
+	  default: 128
+	*/
+	uint64_t ph01_resolution;
+
+	/*
+	semtech,ph23-resolution:
+	  Same as ph01-resolution for phase 2 and 3.
+	*/
+	uint64_t ph23_resolution;
+
+	/*
+	semtech,startup-sensor:
+	  enum: [0, 1, 2, 3]
+	  default: 0
+	  description: |
+	    Phase used for start-up proximity detection.
+	    It is used when we enable a phase to remove static offset and measure
+	    only capacitance changes introduced by the user.
+	*/
+	uint64_t startup_sensor;
+
+	/*
+	semtech,ph01-proxraw-strength:
+	  minimum: 0
+	  maximum: 7
+	  default: 1
+	  description:
+	    PROXRAW filter strength for phase 0 and 1. A value of 0 represents off,
+	    and other values represent 1-1/2^N.
+	*/
+	uint64_t ph01_proxraw_strength;
+
+	/*
+	semtech,ph23-proxraw-strength:
+	  Same as proxraw-strength01, for phase 2 and 3.
+	*/
+	uint64_t ph23_proxraw_strength;
+
+	/*
+	semtech,avg-pos-strength:
+	  enum: [0, 16, 64, 128, 256, 512, 1024, 4294967295]
+	  default: 16
+	  description: |
+	    Average positive filter strength. A value of 0 represents off and
+	    UINT_MAX (4294967295) represents infinite. Other values
+	    represent 1-1/N.
+	*/
+	uint64_t avg_pos_strength;
+
+	/*
+	semtech,cs-idle-sleep:
+	  description:
+	    State of CS pins during sleep mode and idle time.
+	  enum:
+	    - hi-z
+	    - gnd
+	    - vdd
+	*/
+	const char *cs_idle_sleep;
+
+	/*
+	semtech,int-comp-resistor:
+	  description:
+	    Internal resistor setting for compensation.
+	  enum:
+	    - lowest
+	    - low
+	    - high
+	    - highest
+	*/
+	const char *int_comp_resistor;
+
+	/*
+	semtech,input-precharge-resistor-ohms:
+	  default: 4000
+	  multipleOf: 2000
+	  minimum: 0
+	  maximum: 30000
+	  description:
+	    Pre-charge input resistance in Ohm.
+	*/
+	uint64_t input_precharge_resistor_ohms;
+
+	/*
+	semtech,input-analog-gain:
+	  minimum: 0
+	  maximum: 3
+	  description: |
+	    Defines the input antenna analog gain
+	    0: x1.247
+	    1: x1 (default)
+	    2: x0.768
+	    3: x0.552
+	*/
+	uint64_t input_analog_gain;
+
+#if CONFIG(DRIVERS_I2C_SX9324_SUPPORT_LEGACY_LINUX_DRIVER)
 #include "registers.h"
+#endif
 };
 
 #undef REGISTER
diff --git a/src/drivers/i2c/sx9324/registers.h b/src/drivers/i2c/sx9324/registers.h
index 2e225729494a..2035463c4000 100644
--- a/src/drivers/i2c/sx9324/registers.h
+++ b/src/drivers/i2c/sx9324/registers.h
@@ -4,6 +4,10 @@
 #error "define REGISTER(NAME) before including this file"
 #endif
 
+#if !CONFIG(DRIVERS_I2C_SX9324_SUPPORT_LEGACY_LINUX_DRIVER)
+#error "This file is only to support the legacy sx932x linux driver"
+#endif
+
 REGISTER(reg_adv_ctrl0);
 REGISTER(reg_adv_ctrl1);
 REGISTER(reg_adv_ctrl2);
diff --git a/src/drivers/i2c/sx9324/sx9324.c b/src/drivers/i2c/sx9324/sx9324.c
index 2ca9f3634527..367849144f2a 100644
--- a/src/drivers/i2c/sx9324/sx9324.c
+++ b/src/drivers/i2c/sx9324/sx9324.c
@@ -56,7 +56,23 @@ static void i2c_sx9324_fill_ssdt(const struct device *dev)
 
 	/* DSD */
 	dsd = acpi_dp_new_table("_DSD");
+	acpi_dp_add_integer_array(dsd, "semtech,ph0-pin", config->ph0_pin, ARRAY_SIZE(config->ph0_pin));
+	acpi_dp_add_integer_array(dsd, "semtech,ph1-pin", config->ph1_pin, ARRAY_SIZE(config->ph1_pin));
+	acpi_dp_add_integer_array(dsd, "semtech,ph2-pin", config->ph2_pin, ARRAY_SIZE(config->ph2_pin));
+	acpi_dp_add_integer_array(dsd, "semtech,ph3-pin", config->ph3_pin, ARRAY_SIZE(config->ph3_pin));
+	acpi_dp_add_integer(dsd, "semtech,ph01-resolution", config->ph01_resolution);
+	acpi_dp_add_integer(dsd, "semtech,ph23-resolution", config->ph23_resolution);
+	acpi_dp_add_integer(dsd, "semtech,startup-sensor", config->startup_sensor);
+	acpi_dp_add_integer(dsd, "semtech,ph01-proxraw-strength", config->ph01_proxraw_strength);
+	acpi_dp_add_integer(dsd, "semtech,ph23-proxraw-strength", config->ph23_proxraw_strength);
+	acpi_dp_add_integer(dsd, "semtech,avg-pos-strength", config->avg_pos_strength);
+	acpi_dp_add_integer(dsd, "semtech,input-precharge-resistor-ohms", config->input_precharge_resistor_ohms);
+	acpi_dp_add_integer(dsd, "semtech,input-analog-gain", config->input_analog_gain);
+	acpi_dp_add_string(dsd, "semtech,cs-idle-sleep", config->cs_idle_sleep);
+	acpi_dp_add_string(dsd, "semtech,int-comp-resistor", config->int_comp_resistor);
+#if CONFIG(DRIVERS_I2C_SX9324_SUPPORT_LEGACY_LINUX_DRIVER)
 #include "registers.h"
+#endif
 	acpi_dp_write(dsd);
 
 	acpigen_pop_len(); /* Device */