On Thu, Jun 27, 2024 at 09:56:16PM +0530, Ayush Singh wrote:
Adds support for SPI mikroBUS addon boards with configuration based onSo this has nothing to do with greybus? Or am I thinking of something
device tree. The goal is to get a minimal version in mainline to sort
out the device tree structure that should be used.
A mikroBUS board can use any combination of the following based protocols:
I2C, SPI, UART, PWM, Analog, GPIO with possibility of all pins being used
as GPIO instead of their original purpose. This requires the driver to be
flexible and identify the type of board based on the compatible string.
else?
+menuconfig MIKROBUSRemove extra blank line.
+ tristate "Module for instantiating devices on mikroBUS ports"
+ depends on GPIOLIB
+ help
+ This option enables the mikroBUS driver. mikroBUS is an add-on
+ board socket standard that offers maximum expandability with
+ the smallest number of pins. The mikroBUS driver instantiates
+ devices on a mikroBUS port described mikroBUS manifest which is
+ passed using a sysfs interface.
+
+
+ Say Y here to enable support for this driver.This isn't needed.
+KBUILD_MODNAME? Also, why is this needed at all, as you are a
+ To compile this code as a module, chose M here: the module
+ will be called mikrobus.ko
+
source "drivers/misc/c2port/Kconfig"
source "drivers/misc/eeprom/Kconfig"
source "drivers/misc/cb710/Kconfig"
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 153a3f4837e8..f10f1414270b 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -69,3 +69,4 @@ obj-$(CONFIG_TMR_INJECT) += xilinx_tmr_inject.o
obj-$(CONFIG_TPS6594_ESM) += tps6594-esm.o
obj-$(CONFIG_TPS6594_PFSM) += tps6594-pfsm.o
obj-$(CONFIG_NSM) += nsm.o
+obj-$(CONFIG_MIKROBUS) += mikrobus.o
diff --git a/drivers/misc/mikrobus.c b/drivers/misc/mikrobus.c
new file mode 100644
index 000000000000..bf160a0e8903
--- /dev/null
+++ b/drivers/misc/mikrobus.c
@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0:
+/*
+ * Copyright 2024 Ayush Singh <ayush@xxxxxxxxxxxxxxx>
+ */
+
+#define pr_fmt(fmt) "mikrobus:%s: " fmt, __func__
bus/subsystem you should never need a pr_*() call, but instead just use
dev_*() ones instead.
+Documentation? What is "cs"? More vowels please...
+#include <linux/device.h>
+#include <linux/pinctrl/consumer.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/mod_devicetable.h>
+#include <linux/spi/spi.h>
+
+struct mikrobus_spi_cs_item {
+ const char *cs_name;
+ u32 cs;
+};Why must this be a platform device? What requires that?
+
+/**
+ * struct mikrobus_port - MikroBUS Driver
+ *
+ * @dev: underlying platform_device
+ * @board_ocs: board device tree changesetWhat controls the lifespan of this object? You have multiple devices
+ * @pinctrl: mikroBUS pinctrl
+ * @mikrobus_spi_cs: list of supported chipselect address and name
+ * @mikrobus_spi_cs_count: length of mikrobus_spi_cs
+ * @spi_ctrl: spi controller of mikroBUS connector
+ * @spi_dev: spi mikroBUS board
+ */
+struct mikrobus_port {
+ struct platform_device *dev;
+ struct of_changeset board_ocs;
+ struct pinctrl *pctrl;
+
+ struct mikrobus_spi_cs_item *spi_cs;
+ int spi_cs_count;
+ struct spi_controller *spi_ctrl;
+ struct spi_device *spi_dev;
pointed to here with different lifecycles, what controls this one?
+};Either use kerneldoc or not, should be /** right?
+
+/*
+ * mikrobus_pinctrl_select: Select pinctrl state for mikrobus pin
+ *Why rate limited? What is going to cause this to spam the log?
+ * @port: mikrobus port
+ * @pinctrl_selected: pinctrl state to be selected
+ */
+static int mikrobus_pinctrl_select(struct device *dev,
+ const char *pinctrl_selected)
+{
+ int ret;
+ struct pinctrl_state *state;
+ struct mikrobus_port *mb = dev_get_drvdata(dev);
+
+ state = pinctrl_lookup_state(mb->pctrl, pinctrl_selected);
+ if (IS_ERR(state))
+ return dev_err_probe(dev, PTR_ERR(state),
+ "failed to find state %s",
+ pinctrl_selected);
+
+ ret = pinctrl_select_state(mb->pctrl, state);
+ if (ret)
+ return dev_err_probe(dev, ret, "failed to select state %s",
+ pinctrl_selected);
+
+ dev_dbg_ratelimited(dev, "setting pinctrl %s", pinctrl_selected);
+Use "chipselect" instead of "cs" everywhere please.
+ return 0;
+}
+
+/*
+ * mikrobus_lookup_cs - lookup mikroBUS SPI chipselect by name
+ *
+ * @mb: mikroBUS port
+ * @cs_name: chipselect name
+ */what does -1 mean? Use real error numbers please.
+static int mikrobus_lookup_cs(const struct mikrobus_port *mb,
+ const char *cs_name)
+{
+ for (int i = 0; i < mb->spi_cs_count; ++i) {
+ if (strcmp(cs_name, mb->spi_cs[i].cs_name) == 0)
+ return mb->spi_cs[i].cs;
+ }
+
+ return -1;
+}That's some pointer dereferencing without checking anything, what could
+
+static int mikrobus_spi_set_cs(struct device *dev, struct device_node *np)
+{
+ struct mikrobus_port *mb = dev_get_drvdata(dev);
+ const char *temp_str;
+ int reg_len;
+ int ret, i;
+ u32 *reg = NULL;
+
+ reg_len = of_property_count_strings(np, "spi-cs");
+ /* Use default cs if spi-cs property not present */
+ if (reg_len <= 0) {
+ reg_len = 1;
+ reg = devm_kmalloc_array(dev, reg_len, sizeof(*reg),
+ GFP_KERNEL);
+ if (!reg)
+ return -ENOMEM;
+
+ ret = mikrobus_lookup_cs(mb, "default");
+ if (ret < 0)
+ goto free_reg;
+
+ reg[0] = ret;
+ } else {
+ reg = devm_kmalloc_array(dev, reg_len, sizeof(*reg),
+ GFP_KERNEL);
+ if (!reg)
+ return -ENOMEM;
+
+ for (i = 0; i < reg_len; ++i) {
+ ret = of_property_read_string_index(np, "spi-cs", i,
+ &temp_str);
+ if (ret < 0)
+ goto free_reg;
+
+ ret = mikrobus_lookup_cs(mb, temp_str);
+ if (ret < 0)
+ goto free_reg;
+
+ reg[i] = ret;
+ }
+ }
+
+ ret = of_changeset_add_prop_u32_array(&mb->board_ocs, np, "reg", reg,
+ reg_len);
+ if (ret < 0)
+ goto free_reg;
+
+ ret = of_changeset_apply(&mb->board_ocs);
+ if (ret < 0)
+ goto free_reg;
+
+ devm_kfree(dev, reg);
+ return 0;
+
+free_reg:
+ devm_kfree(dev, reg);
+ return ret;
+}
+
+static int of_register_mikrobus_device(struct mikrobus_port *mb,
+ struct device_node *np)
+{
+ const char *temp_str;
+ int i, pinctrl_count, ret;
+ struct spi_device *spi_dev;
+ struct device *dev = &mb->dev->dev;
go wrong...
Why don't you have your own real device? Why are you relying on a
platform device without actually showing your device anywhere in the
kernel's device topology? Are you sure that is ok?
+Again, why is this a platform driver? Why is a platform device used at
+ pinctrl_count = of_property_count_strings(np, "pinctrl-apply");
+ if (pinctrl_count < 0)
+ return dev_err_probe(dev, pinctrl_count,
+ "Missing required property pinctrl-apply");
+
+ for (i = 0; i < pinctrl_count; ++i) {
+ ret = of_property_read_string_index(np, "pinctrl-apply", i,
+ &temp_str);
+ if (ret < 0)
+ return ret;
+
+ ret = mikrobus_pinctrl_select(dev, temp_str);
+ if (ret < 0)
+ return dev_err_probe(dev, ret, "Failed to set pinctrl");
+ }
+
+ if (mb->spi_ctrl && !mb->spi_dev &&
+ of_device_is_compatible(np, "mikrobus-spi")) {
+ ret = mikrobus_spi_set_cs(dev, np);
+ if (ret < 0)
+ return dev_err_probe(dev, ret,
+ "Failed to set SPI chipselect");
+
+ spi_dev = of_register_spi_device(mb->spi_ctrl, np);
+ if (IS_ERR(spi_dev))
+ return dev_err_probe(dev, PTR_ERR(spi_dev),
+ "Failed to register SPI device");
+ mb->spi_dev = spi_dev;
+ }
+
+ return 0;
+}
+
+static int of_register_mikrobus_board(struct mikrobus_port *mb)
+{
+ struct device *dev = &mb->dev->dev;
+ int board_len, i, ret;
+ struct device_node *np;
+
+ board_len = of_count_phandle_with_args(dev->of_node, "board", NULL);
+ for (i = 0; i < board_len; ++i) {
+ np = of_parse_phandle(dev->of_node, "board", i);
+ if (!np) {
+ ret = dev_err_probe(dev, -ENODEV, "Board not found");
+ goto free_np;
+ }
+
+ ret = of_register_mikrobus_device(mb, np);
+ if (ret < 0)
+ goto free_np;
+
+ of_node_put(np);
+ }
+
+ return 0;
+free_np:
+ of_node_put(np);
+ return ret;
+}
+
+static int mikrobus_port_probe(struct platform_device *pdev)
+{
+ int ret, i;
+ struct mikrobus_port *mb;
+ struct device_node *np;
+ struct device *dev = &pdev->dev;
+
+ mb = devm_kmalloc(dev, sizeof(*mb), GFP_KERNEL);
+ if (!mb)
+ return -ENOMEM;
+
+ dev_set_drvdata(dev, mb);
+
+ of_changeset_init(&mb->board_ocs);
+ mb->dev = pdev;
+ mb->pctrl = NULL;
+ mb->spi_ctrl = NULL;
+ mb->spi_dev = NULL;
+ mb->spi_cs = NULL;
+ mb->spi_cs_count = 0;
+
+ mb->pctrl = devm_pinctrl_get(dev);
+ if (IS_ERR(mb->pctrl))
+ return dev_err_probe(dev, PTR_ERR(mb->pctrl),
+ "failed to get pinctrl [%ld]",
+ PTR_ERR(mb->pctrl));
+
+ np = of_parse_phandle(dev->of_node, "spi-controller", 0);
+ if (np) {
+ mb->spi_ctrl = of_find_spi_controller_by_node(np);
+ if (mb->spi_ctrl) {
+ ret = of_property_count_u32_elems(dev->of_node,
+ "spi-cs");
+ if (ret < 0) {
+ dev_err(dev, "Missing property spi-cs");
+ goto free_np;
+ }
+
+ mb->spi_cs_count = ret;
+
+ ret = of_property_count_strings(dev->of_node,
+ "spi-cs-names");
+ if (ret < 0) {
+ dev_err(dev, "Missing property spi-cs-names");
+ goto free_np;
+ }
+
+ if (mb->spi_cs_count != ret) {
+ ret = dev_err_probe(
+ dev, -EINVAL,
+ "spi-cs and spi-cs-names out of sync");
+ goto free_np;
+ }
+
+ mb->spi_cs = devm_kmalloc_array(dev, mb->spi_cs_count,
+ sizeof(*mb->spi_cs),
+ GFP_KERNEL);
+ if (!mb->spi_cs) {
+ ret = -ENOMEM;
+ goto free_np;
+ }
+
+ for (i = 0; i < mb->spi_cs_count; ++i) {
+ of_property_read_u32_index(dev->of_node,
+ "spi-cs", i,
+ &mb->spi_cs->cs);
+ of_property_read_string_index(
+ dev->of_node, "spi-cs-names", i,
+ &mb->spi_cs->cs_name);
+ }
+ }
+ }
+ of_node_put(np);
+
+ ret = of_register_mikrobus_board(mb);
+ if (ret < 0)
+ return dev_err_probe(dev, -EINVAL,
+ "Failed to register mikrobus board");
+
+ return 0;
+
+free_np:
+ of_node_put(np);
+ return ret;
+}
+
+static void mikrobus_port_remove(struct platform_device *pdev)
+{
+ struct mikrobus_port *mb = dev_get_drvdata(&pdev->dev);
+
+ spi_unregister_device(mb->spi_dev);
+
+ of_changeset_revert(&mb->board_ocs);
+}
+
+static const struct of_device_id mikrobus_port_of_match[] = {
+ { .compatible = "mikrobus-connector" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mikrobus_port_of_match);
+
+static struct platform_driver mikrobus_port_driver = {
+ .probe = mikrobus_port_probe,
+ .remove = mikrobus_port_remove,
all here?
+ .driver = {It fails yet you leave your bus around? Not good :(
+ .name = "mikrobus",
+ .of_match_table = mikrobus_port_of_match,
+ },
+};
+
+static const struct bus_type mikrobus_bus_type = {
+ .name = "mikrobus",
+};
+
+static int mikrobus_init(void)
+{
+ int ret;
+
+ ret = bus_register(&mikrobus_bus_type);
+ if (ret) {
+ pr_err("bus_register failed (%d)", ret);
+ return ret;
+ }
+
+ ret = platform_driver_register(&mikrobus_port_driver);
+ if (ret)
+ pr_err("driver register failed [%d]", ret);
thanks,
greg k-h