在 2023/3/8 下午11:03, Mark Brown 写道:
On Wed, Mar 08, 2023 at 10:59:08AM +0800, Yinbo Zhu wrote:
+config SPI_LOONGSON
+ tristate "Loongson SPI Controller Support"
+ depends on LOONGARCH && OF && PCI
I'm not seeing any build time dependencies here (possibly PCI?) so
please add an || COMPILE_TEST to improve build coverage. It'd be better
to have separate modules for the platform and PCI functionality, that
way someone who has a system without PCI can still use the driver even
with PCI support disabled.
I will add an || COMPILE_TEST and drop && PCI then add some CONFIG_PCI
macro
to limit some pci code.
+++ b/drivers/spi/spi-loongson.c
@@ -0,0 +1,502 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Loongson SPI Support
+ *
+ * Copyright (C) 2023 Loongson Technology Corporation Limited
Please make the entire comment block a C++ one so things look more
intentional.
okay, I got it.
+static int loongson_spi_update_state(struct loongson_spi *loongson_spi,
+ struct spi_device *spi, struct spi_transfer *t)
+{
+ unsigned int hz;
+ unsigned int div, div_tmp;
+ unsigned int bit;
+ unsigned char val;
+ const char rdiv[12] = {0, 1, 4, 2, 3, 5, 6, 7, 8, 9, 10, 11};
+
+ hz = t ? t->speed_hz : spi->max_speed_hz;
Please write normal conditional statements so that things are legible,
though in this case the core will ensure that there's a speed_hz in
every transfer so there's no need for any of the logic around ensuring
it's set.
Do you mean to achieve the following ? and drop spi->max_speed_hz.
if (t)
hz = t->speed_hz;
+static int loongson_spi_setup(struct spi_device *spi)
+{
+ struct loongson_spi *loongson_spi;
+
+ loongson_spi = spi_master_get_devdata(spi->master);
+ if (spi->bits_per_word % 8)
+ return -EINVAL;
+
+ if (spi->chip_select >= spi->master->num_chipselect)
+ return -EINVAL;
+
+ loongson_spi_update_state(loongson_spi, spi, NULL);
+ loongson_spi_set_cs(loongson_spi, spi, 1);
Note that setup() needs to be able to run for one device while there are
transfers for other devices on the same controller active.
okay, I will add a spin_lock for it.
+static int loongson_spi_write_read_8bit(struct spi_device *spi, const u8 **tx_buf,
+ u8 **rx_buf, unsigned int num)
+{
+ struct loongson_spi *loongson_spi = spi_master_get_devdata(spi->master);
+
+ if (tx_buf && *tx_buf) {
+ loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_FIFO_REG, *((*tx_buf)++));
+ while ((loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_SPSR_REG) & 0x1) == 1)
+ ;
A timeout would be good on these spins in case the controller gets
stuck. It'd also be polite to have a cpu_relax() somewhere either here
or in the caller given that it's busy waiting.
okay, I got it.
+static void loongson_spi_work(struct work_struct *work)
+{
+ int param;
+ struct spi_message *m;
+ struct spi_device *spi;
+ struct spi_transfer *t = NULL;
+ struct loongson_spi *loongson_spi = container_of(work, struct loongson_spi, work);
+
+ spin_lock(&loongson_spi->lock);
+ param = loongson_spi_read_reg(loongson_spi, LOONGSON_SPI_PARA_REG);
+ loongson_spi_write_reg(loongson_spi, LOONGSON_SPI_PARA_REG, param&~1);
+ while (!list_empty(&loongson_spi->msg_queue)) {
+ m = container_of(loongson_spi->msg_queue.next, struct spi_message, queue);
+
This all looks like it's open coding the core's message pump, only
without the heavy optimisation work that the core has and missing some
handling of cs_change and delays. You should implement
spi_transfer_one() instead, this will save a lot of code and should be
more performant.
okay, I will try to add a spi_transfer_one for this.
+static int loongson_spi_transfer(struct spi_device *spi, struct spi_message *m)
+{
In general you'd need an extremely strong reason to implement transfer()
in a new driver.
okay, I got it.
+static int __maybe_unused loongson_spi_resume(struct device *dev)
+{
+static const struct dev_pm_ops loongson_spi_dev_pm_ops = {
+ .suspend = loongson_spi_suspend,
+ .resume = loongson_spi_resume,
+};
The suspend/resume ops are assigned unconditionally.
sorry, I don't got it, you mean was to add a CONFIG_PM to limit code ?
+subsys_initcall(loongson_spi_init);
+module_exit(loongson_spi_exit);
Why not just a regular module initcall like most SPI drivers?
okay, I will use module_init for register spi drivers.
