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Subject[PATCH 04/13] staging: mt7621-spi: add mt7621 support
From: John Crispin <blogic@openwrt.org>

NeilBrown:
The code will fail with a warning if asked to transfer
more than 32 bytes at a time. So used max_transfer_size
interface to tell users about this.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: NeilBrown <neil@brown.name>
---
drivers/staging/Kconfig | 2
drivers/staging/Makefile | 1
drivers/staging/mt7621-spi/Kconfig | 6
drivers/staging/mt7621-spi/Makefile | 1
drivers/staging/mt7621-spi/TODO | 5
drivers/staging/mt7621-spi/spi-mt7621.c | 489 +++++++++++++++++++++++++++++++
6 files changed, 504 insertions(+)
create mode 100644 drivers/staging/mt7621-spi/Kconfig
create mode 100644 drivers/staging/mt7621-spi/Makefile
create mode 100644 drivers/staging/mt7621-spi/TODO
create mode 100644 drivers/staging/mt7621-spi/spi-mt7621.c

diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 7568e10399fa..bcc6da1f656a 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -126,4 +126,6 @@ source "drivers/staging/mt7621-pinctrl/Kconfig"

source "drivers/staging/mt7621-gpio/Kconfig"

+source "drivers/staging/mt7621-spi/Kconfig"
+
endif # STAGING
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 609fdb218985..051af9965549 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -55,3 +55,4 @@ obj-$(CONFIG_PI433) += pi433/
obj-$(CONFIG_SOC_MT7621) += mt7621-pci/
obj-$(CONFIG_SOC_MT7621) += mt7621-pinctrl/
obj-$(CONFIG_SOC_MT7621) += mt7621-gpio/
+obj-$(CONFIG_SOC_MT7621) += mt7621-spi/
diff --git a/drivers/staging/mt7621-spi/Kconfig b/drivers/staging/mt7621-spi/Kconfig
new file mode 100644
index 000000000000..0b90f4cfa426
--- /dev/null
+++ b/drivers/staging/mt7621-spi/Kconfig
@@ -0,0 +1,6 @@
+config SPI_MT7621
+ tristate "MediaTek MT7621 SPI Controller"
+ depends on RALINK
+ help
+ This selects a driver for the MediaTek MT7621 SPI Controller.
+
diff --git a/drivers/staging/mt7621-spi/Makefile b/drivers/staging/mt7621-spi/Makefile
new file mode 100644
index 000000000000..3be508f63bac
--- /dev/null
+++ b/drivers/staging/mt7621-spi/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_SPI_MT7621) += spi-mt7621.o
diff --git a/drivers/staging/mt7621-spi/TODO b/drivers/staging/mt7621-spi/TODO
new file mode 100644
index 000000000000..fdbc5002c32a
--- /dev/null
+++ b/drivers/staging/mt7621-spi/TODO
@@ -0,0 +1,5 @@
+
+- general code review and clean up
+- ensure device-tree requirements are documented
+
+Cc: NeilBrown <neil@brown.name>
diff --git a/drivers/staging/mt7621-spi/spi-mt7621.c b/drivers/staging/mt7621-spi/spi-mt7621.c
new file mode 100644
index 000000000000..d95e0b32f1f0
--- /dev/null
+++ b/drivers/staging/mt7621-spi/spi-mt7621.c
@@ -0,0 +1,489 @@
+/*
+ * spi-mt7621.c -- MediaTek MT7621 SPI controller driver
+ *
+ * Copyright (C) 2011 Sergiy <piratfm@gmail.com>
+ * Copyright (C) 2011-2013 Gabor Juhos <juhosg@openwrt.org>
+ * Copyright (C) 2014-2015 Felix Fietkau <nbd@nbd.name>
+ *
+ * Some parts are based on spi-orion.c:
+ * Author: Shadi Ammouri <shadi@marvell.com>
+ * Copyright (C) 2007-2008 Marvell Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/reset.h>
+#include <linux/spi/spi.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/swab.h>
+
+#include <ralink_regs.h>
+
+#define SPI_BPW_MASK(bits) BIT((bits) - 1)
+
+#define DRIVER_NAME "spi-mt7621"
+/* in usec */
+#define RALINK_SPI_WAIT_MAX_LOOP 2000
+
+/* SPISTAT register bit field */
+#define SPISTAT_BUSY BIT(0)
+
+#define MT7621_SPI_TRANS 0x00
+#define SPITRANS_BUSY BIT(16)
+
+#define MT7621_SPI_OPCODE 0x04
+#define MT7621_SPI_DATA0 0x08
+#define MT7621_SPI_DATA4 0x18
+#define SPI_CTL_TX_RX_CNT_MASK 0xff
+#define SPI_CTL_START BIT(8)
+
+#define MT7621_SPI_POLAR 0x38
+#define MT7621_SPI_MASTER 0x28
+#define MT7621_SPI_MOREBUF 0x2c
+#define MT7621_SPI_SPACE 0x3c
+
+#define MT7621_CPHA BIT(5)
+#define MT7621_CPOL BIT(4)
+#define MT7621_LSB_FIRST BIT(3)
+
+#define RT2880_SPI_MODE_BITS (SPI_CPOL | SPI_CPHA | SPI_LSB_FIRST | SPI_CS_HIGH)
+
+struct mt7621_spi;
+
+struct mt7621_spi {
+ struct spi_master *master;
+ void __iomem *base;
+ unsigned int sys_freq;
+ unsigned int speed;
+ struct clk *clk;
+ spinlock_t lock;
+
+ struct mt7621_spi_ops *ops;
+};
+
+static inline struct mt7621_spi *spidev_to_mt7621_spi(struct spi_device *spi)
+{
+ return spi_master_get_devdata(spi->master);
+}
+
+static inline u32 mt7621_spi_read(struct mt7621_spi *rs, u32 reg)
+{
+ return ioread32(rs->base + reg);
+}
+
+static inline void mt7621_spi_write(struct mt7621_spi *rs, u32 reg, u32 val)
+{
+ iowrite32(val, rs->base + reg);
+}
+
+static void mt7621_spi_reset(struct mt7621_spi *rs, int duplex)
+{
+ u32 master = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+
+ master |= 7 << 29;
+ master |= 1 << 2;
+ if (duplex)
+ master |= 1 << 10;
+ else
+ master &= ~(1 << 10);
+
+ mt7621_spi_write(rs, MT7621_SPI_MASTER, master);
+}
+
+static void mt7621_spi_set_cs(struct spi_device *spi, int enable)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+ int cs = spi->chip_select;
+ u32 polar = 0;
+
+ mt7621_spi_reset(rs, cs);
+ if (enable)
+ polar = BIT(cs);
+ mt7621_spi_write(rs, MT7621_SPI_POLAR, polar);
+}
+
+static int mt7621_spi_prepare(struct spi_device *spi, unsigned int speed)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+ u32 rate;
+ u32 reg;
+
+ dev_dbg(&spi->dev, "speed:%u\n", speed);
+
+ rate = DIV_ROUND_UP(rs->sys_freq, speed);
+ dev_dbg(&spi->dev, "rate-1:%u\n", rate);
+
+ if (rate > 4097)
+ return -EINVAL;
+
+ if (rate < 2)
+ rate = 2;
+
+ reg = mt7621_spi_read(rs, MT7621_SPI_MASTER);
+ reg &= ~(0xfff << 16);
+ reg |= (rate - 2) << 16;
+ rs->speed = speed;
+
+ reg &= ~MT7621_LSB_FIRST;
+ if (spi->mode & SPI_LSB_FIRST)
+ reg |= MT7621_LSB_FIRST;
+
+ reg &= ~(MT7621_CPHA | MT7621_CPOL);
+ switch(spi->mode & (SPI_CPOL | SPI_CPHA)) {
+ case SPI_MODE_0:
+ break;
+ case SPI_MODE_1:
+ reg |= MT7621_CPHA;
+ break;
+ case SPI_MODE_2:
+ reg |= MT7621_CPOL;
+ break;
+ case SPI_MODE_3:
+ reg |= MT7621_CPOL | MT7621_CPHA;
+ break;
+ }
+ mt7621_spi_write(rs, MT7621_SPI_MASTER, reg);
+
+ return 0;
+}
+
+static inline int mt7621_spi_wait_till_ready(struct spi_device *spi)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+ int i;
+
+ for (i = 0; i < RALINK_SPI_WAIT_MAX_LOOP; i++) {
+ u32 status;
+
+ status = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+ if ((status & SPITRANS_BUSY) == 0) {
+ return 0;
+ }
+ cpu_relax();
+ udelay(1);
+ }
+
+ return -ETIMEDOUT;
+}
+
+static int mt7621_spi_transfer_half_duplex(struct spi_master *master,
+ struct spi_message *m)
+{
+ struct mt7621_spi *rs = spi_master_get_devdata(master);
+ struct spi_device *spi = m->spi;
+ unsigned int speed = spi->max_speed_hz;
+ struct spi_transfer *t = NULL;
+ int status = 0;
+ int i, len = 0;
+ int rx_len = 0;
+ u32 data[9] = { 0 };
+ u32 val;
+
+ mt7621_spi_wait_till_ready(spi);
+
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ const u8 *buf = t->tx_buf;
+
+ if (t->rx_buf)
+ rx_len += t->len;
+
+ if (!buf)
+ continue;
+
+ if (t->speed_hz < speed)
+ speed = t->speed_hz;
+
+ if (WARN_ON(len + t->len > 36)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ for (i = 0; i < t->len; i++, len++)
+ data[len / 4] |= buf[i] << (8 * (len & 3));
+ }
+
+ if (WARN_ON(rx_len > 32)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ if (mt7621_spi_prepare(spi, speed)) {
+ status = -EIO;
+ goto msg_done;
+ }
+ data[0] = swab32(data[0]);
+ if (len < 4)
+ data[0] >>= (4 - len) * 8;
+
+ for (i = 0; i < len; i += 4)
+ mt7621_spi_write(rs, MT7621_SPI_OPCODE + i, data[i / 4]);
+
+ val = (min_t(int, len, 4) * 8) << 24;
+ if (len > 4)
+ val |= (len - 4) * 8;
+ val |= (rx_len * 8) << 12;
+ mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
+
+ mt7621_spi_set_cs(spi, 1);
+
+ val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+ val |= SPI_CTL_START;
+ mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
+
+ mt7621_spi_wait_till_ready(spi);
+
+ mt7621_spi_set_cs(spi, 0);
+
+ for (i = 0; i < rx_len; i += 4)
+ data[i / 4] = mt7621_spi_read(rs, MT7621_SPI_DATA0 + i);
+
+ m->actual_length = len + rx_len;
+
+ len = 0;
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ u8 *buf = t->rx_buf;
+
+ if (!buf)
+ continue;
+
+ for (i = 0; i < t->len; i++, len++)
+ buf[i] = data[len / 4] >> (8 * (len & 3));
+ }
+
+msg_done:
+ m->status = status;
+ spi_finalize_current_message(master);
+
+ return 0;
+}
+
+static int mt7621_spi_transfer_full_duplex(struct spi_master *master,
+ struct spi_message *m)
+{
+ struct mt7621_spi *rs = spi_master_get_devdata(master);
+ struct spi_device *spi = m->spi;
+ unsigned int speed = spi->max_speed_hz;
+ struct spi_transfer *t = NULL;
+ int status = 0;
+ int i, len = 0;
+ int rx_len = 0;
+ u32 data[9] = { 0 };
+ u32 val = 0;
+
+ mt7621_spi_wait_till_ready(spi);
+
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ const u8 *buf = t->tx_buf;
+
+ if (t->rx_buf)
+ rx_len += t->len;
+
+ if (!buf)
+ continue;
+
+ if (WARN_ON(len + t->len > 16)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ for (i = 0; i < t->len; i++, len++)
+ data[len / 4] |= buf[i] << (8 * (len & 3));
+ if (speed > t->speed_hz)
+ speed = t->speed_hz;
+ }
+
+ if (WARN_ON(rx_len > 16)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ if (mt7621_spi_prepare(spi, speed)) {
+ status = -EIO;
+ goto msg_done;
+ }
+
+ for (i = 0; i < len; i += 4)
+ mt7621_spi_write(rs, MT7621_SPI_DATA0 + i, data[i / 4]);
+
+ val |= len * 8;
+ val |= (rx_len * 8) << 12;
+ mt7621_spi_write(rs, MT7621_SPI_MOREBUF, val);
+
+ mt7621_spi_set_cs(spi, 1);
+
+ val = mt7621_spi_read(rs, MT7621_SPI_TRANS);
+ val |= SPI_CTL_START;
+ mt7621_spi_write(rs, MT7621_SPI_TRANS, val);
+
+ mt7621_spi_wait_till_ready(spi);
+
+ mt7621_spi_set_cs(spi, 0);
+
+ for (i = 0; i < rx_len; i += 4)
+ data[i / 4] = mt7621_spi_read(rs, MT7621_SPI_DATA4 + i);
+
+ m->actual_length = rx_len;
+
+ len = 0;
+ list_for_each_entry(t, &m->transfers, transfer_list) {
+ u8 *buf = t->rx_buf;
+
+ if (!buf)
+ continue;
+
+ for (i = 0; i < t->len; i++, len++)
+ buf[i] = data[len / 4] >> (8 * (len & 3));
+ }
+
+msg_done:
+ m->status = status;
+ spi_finalize_current_message(master);
+
+ return 0;
+}
+
+static int mt7621_spi_transfer_one_message(struct spi_master *master,
+ struct spi_message *m)
+{
+ struct spi_device *spi = m->spi;
+ int cs = spi->chip_select;
+
+ if (cs)
+ return mt7621_spi_transfer_full_duplex(master, m);
+ return mt7621_spi_transfer_half_duplex(master, m);
+}
+
+static int mt7621_spi_setup(struct spi_device *spi)
+{
+ struct mt7621_spi *rs = spidev_to_mt7621_spi(spi);
+
+ if ((spi->max_speed_hz == 0) ||
+ (spi->max_speed_hz > (rs->sys_freq / 2)))
+ spi->max_speed_hz = (rs->sys_freq / 2);
+
+ if (spi->max_speed_hz < (rs->sys_freq / 4097)) {
+ dev_err(&spi->dev, "setup: requested speed is too low %d Hz\n",
+ spi->max_speed_hz);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static const struct of_device_id mt7621_spi_match[] = {
+ { .compatible = "ralink,mt7621-spi" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mt7621_spi_match);
+
+static size_t max_transfer_size(struct spi_device *spi)
+{
+ return 32;
+}
+
+static int mt7621_spi_probe(struct platform_device *pdev)
+{
+ const struct of_device_id *match;
+ struct spi_master *master;
+ struct mt7621_spi *rs;
+ unsigned long flags;
+ void __iomem *base;
+ struct resource *r;
+ int status = 0;
+ struct clk *clk;
+ struct mt7621_spi_ops *ops;
+
+ match = of_match_device(mt7621_spi_match, &pdev->dev);
+ if (!match)
+ return -EINVAL;
+ ops = (struct mt7621_spi_ops *)match->data;
+
+ r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ base = devm_ioremap_resource(&pdev->dev, r);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ clk = devm_clk_get(&pdev->dev, NULL);
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "unable to get SYS clock, err=%d\n",
+ status);
+ return PTR_ERR(clk);
+ }
+
+ status = clk_prepare_enable(clk);
+ if (status)
+ return status;
+
+ master = spi_alloc_master(&pdev->dev, sizeof(*rs));
+ if (master == NULL) {
+ dev_info(&pdev->dev, "master allocation failed\n");
+ return -ENOMEM;
+ }
+
+ master->mode_bits = RT2880_SPI_MODE_BITS;
+
+ master->setup = mt7621_spi_setup;
+ master->transfer_one_message = mt7621_spi_transfer_one_message;
+ master->bits_per_word_mask = SPI_BPW_MASK(8);
+ master->dev.of_node = pdev->dev.of_node;
+ master->num_chipselect = 2;
+ master->max_transfer_size = max_transfer_size;
+
+ dev_set_drvdata(&pdev->dev, master);
+
+ rs = spi_master_get_devdata(master);
+ rs->base = base;
+ rs->clk = clk;
+ rs->master = master;
+ rs->sys_freq = clk_get_rate(rs->clk);
+ rs->ops = ops;
+ dev_info(&pdev->dev, "sys_freq: %u\n", rs->sys_freq);
+ spin_lock_irqsave(&rs->lock, flags);
+
+ device_reset(&pdev->dev);
+
+ mt7621_spi_reset(rs, 0);
+
+ return spi_register_master(master);
+}
+
+static int mt7621_spi_remove(struct platform_device *pdev)
+{
+ struct spi_master *master;
+ struct mt7621_spi *rs;
+
+ master = dev_get_drvdata(&pdev->dev);
+ rs = spi_master_get_devdata(master);
+
+ clk_disable(rs->clk);
+ spi_unregister_master(master);
+
+ return 0;
+}
+
+MODULE_ALIAS("platform:" DRIVER_NAME);
+
+static struct platform_driver mt7621_spi_driver = {
+ .driver = {
+ .name = DRIVER_NAME,
+ .owner = THIS_MODULE,
+ .of_match_table = mt7621_spi_match,
+ },
+ .probe = mt7621_spi_probe,
+ .remove = mt7621_spi_remove,
+};
+
+module_platform_driver(mt7621_spi_driver);
+
+MODULE_DESCRIPTION("MT7621 SPI driver");
+MODULE_AUTHOR("Felix Fietkau <nbd@nbd.name>");
+MODULE_LICENSE("GPL");

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