spi: meson: Add support for Amlogic Meson SPIFC

This is a driver for the Amlogic Meson SPIFC (SPI flash controller),
which is one of the two SPI controllers available on the SoC. It
doesn't support DMA and has a 64-byte unified transmit/receive buffer.

The device is optimized for interfacing with SPI NOR memories and
allows the execution of standard operations such as read, page
program, sector erase, etc. in a simplified way, toggling a bit in a
dedicated register. The driver doesn't use those predefined commands
and relies only on custom transfers.

Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

3 files changed, 470 insertions, 0 deletions

diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 84e7c9e6ccef..70f20b99e5ff 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -301,6 +301,13 @@ config SPI_FSL_ESPI
           From MPC8536, 85xx platform uses the controller, and all P10xx,
           P20xx, P30xx,P40xx, P50xx uses this controller.
 
+config SPI_MESON_SPIFC
+        tristate "Amlogic Meson SPIFC controller"
+        depends on ARCH_MESON || COMPILE_TEST
+        help
+          This enables master mode support for the SPIFC (SPI flash
+          controller) available in Amlogic Meson SoCs.
+
 config SPI_OC_TINY
         tristate "OpenCores tiny SPI"
         depends on GPIOLIB
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 78f24ca36fcf..9b8a7472b5b8 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -42,6 +42,7 @@ obj-$(CONFIG_SPI_FSL_SPI)		+= spi-fsl-spi.o
 obj-$(CONFIG_SPI_GPIO)                  += spi-gpio.o
 obj-$(CONFIG_SPI_IMX)                   += spi-imx.o
 obj-$(CONFIG_SPI_LM70_LLP)              += spi-lm70llp.o
+obj-$(CONFIG_SPI_MESON_SPIFC)           += spi-meson-spifc.o
 obj-$(CONFIG_SPI_MPC512x_PSC)           += spi-mpc512x-psc.o
 obj-$(CONFIG_SPI_MPC52xx_PSC)           += spi-mpc52xx-psc.o
 obj-$(CONFIG_SPI_MPC52xx)               += spi-mpc52xx.o
diff --git a/drivers/spi/spi-meson-spifc.c b/drivers/spi/spi-meson-spifc.c
new file mode 100644
index 000000000000..f536476710ad
--- /dev/null
+++ b/drivers/spi/spi-meson-spifc.c
@@ -0,0 +1,462 @@
+/*
+ * Driver for Amlogic Meson SPI flash controller (SPIFC)
+ *
+ * Copyright (C) 2014 Beniamino Galvani <b.galvani@gmail.com>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+#include <linux/types.h>
+
+/* register map */
+#define REG_CMD                 0x00
+#define REG_ADDR                0x04
+#define REG_CTRL                0x08
+#define REG_CTRL1               0x0c
+#define REG_STATUS              0x10
+#define REG_CTRL2               0x14
+#define REG_CLOCK               0x18
+#define REG_USER                0x1c
+#define REG_USER1               0x20
+#define REG_USER2               0x24
+#define REG_USER3               0x28
+#define REG_USER4               0x2c
+#define REG_SLAVE               0x30
+#define REG_SLAVE1              0x34
+#define REG_SLAVE2              0x38
+#define REG_SLAVE3              0x3c
+#define REG_C0                  0x40
+#define REG_B8                  0x60
+#define REG_MAX                 0x7c
+
+/* register fields */
+#define CMD_USER                BIT(18)
+#define CTRL_ENABLE_AHB         BIT(17)
+#define CLOCK_SOURCE            BIT(31)
+#define CLOCK_DIV_SHIFT         12
+#define CLOCK_DIV_MASK          (0x3f << CLOCK_DIV_SHIFT)
+#define CLOCK_CNT_HIGH_SHIFT    6
+#define CLOCK_CNT_HIGH_MASK     (0x3f << CLOCK_CNT_HIGH_SHIFT)
+#define CLOCK_CNT_LOW_SHIFT     0
+#define CLOCK_CNT_LOW_MASK      (0x3f << CLOCK_CNT_LOW_SHIFT)
+#define USER_DIN_EN_MS          BIT(0)
+#define USER_CMP_MODE           BIT(2)
+#define USER_UC_DOUT_SEL        BIT(27)
+#define USER_UC_DIN_SEL         BIT(28)
+#define USER_UC_MASK            ((BIT(5) - 1) << 27)
+#define USER1_BN_UC_DOUT_SHIFT  17
+#define USER1_BN_UC_DOUT_MASK   (0xff << 16)
+#define USER1_BN_UC_DIN_SHIFT   8
+#define USER1_BN_UC_DIN_MASK    (0xff << 8)
+#define USER4_CS_ACT            BIT(30)
+#define SLAVE_TRST_DONE         BIT(4)
+#define SLAVE_OP_MODE           BIT(30)
+#define SLAVE_SW_RST            BIT(31)
+
+#define SPIFC_BUFFER_SIZE       64
+
+/**
+ * struct meson_spifc
+ * @master:     the SPI master
+ * @regmap:     regmap for device registers
+ * @clk:        input clock of the built-in baud rate generator
+ * @device:     the device structure
+ */
+struct meson_spifc {
+        struct spi_master *master;
+        struct regmap *regmap;
+        struct clk *clk;
+        struct device *dev;
+};
+
+static struct regmap_config spifc_regmap_config = {
+        .reg_bits = 32,
+        .val_bits = 32,
+        .reg_stride = 4,
+        .max_register = REG_MAX,
+};
+
+/**
+ * meson_spifc_wait_ready() - wait for the current operation to terminate
+ * @spifc:      the Meson SPI device
+ * Return:      0 on success, a negative value on error
+ */
+static int meson_spifc_wait_ready(struct meson_spifc *spifc)
+{
+        unsigned long deadline = jiffies + msecs_to_jiffies(5);
+        u32 data;
+
+        do {
+                regmap_read(spifc->regmap, REG_SLAVE, &data);
+                if (data & SLAVE_TRST_DONE)
+                        return 0;
+                cond_resched();
+        } while (!time_after(jiffies, deadline));
+
+        return -ETIMEDOUT;
+}
+
+/**
+ * meson_spifc_drain_buffer() - copy data from device buffer to memory
+ * @spifc:      the Meson SPI device
+ * @buf:        the destination buffer
+ * @len:        number of bytes to copy
+ */
+static void meson_spifc_drain_buffer(struct meson_spifc *spifc, u8 *buf,
+                                     int len)
+{
+        u32 data;
+        int i = 0;
+
+        while (i < len) {
+                regmap_read(spifc->regmap, REG_C0 + i, &data);
+
+                if (len - i >= 4) {
+                        *((u32 *)buf) = data;
+                        buf += 4;
+                } else {
+                        memcpy(buf, &data, len - i);
+                        break;
+                }
+                i += 4;
+        }
+}
+
+/**
+ * meson_spifc_fill_buffer() - copy data from memory to device buffer
+ * @spifc:      the Meson SPI device
+ * @buf:        the source buffer
+ * @len:        number of bytes to copy
+ */
+static void meson_spifc_fill_buffer(struct meson_spifc *spifc, const u8 *buf,
+                                    int len)
+{
+        u32 data;
+        int i = 0;
+
+        while (i < len) {
+                if (len - i >= 4)
+                        data = *(u32 *)buf;
+                else
+                        memcpy(&data, buf, len - i);
+
+                regmap_write(spifc->regmap, REG_C0 + i, data);
+
+                buf += 4;
+                i += 4;
+        }
+}
+
+/**
+ * meson_spifc_setup_speed() - program the clock divider
+ * @spifc:      the Meson SPI device
+ * @speed:      desired speed in Hz
+ */
+void meson_spifc_setup_speed(struct meson_spifc *spifc, u32 speed)
+{
+        unsigned long parent, value;
+        int n;
+
+        parent = clk_get_rate(spifc->clk);
+        n = max_t(int, parent / speed - 1, 1);
+
+        dev_dbg(spifc->dev, "parent %lu, speed %u, n %d\n", parent,
+                speed, n);
+
+        value = (n << CLOCK_DIV_SHIFT) & CLOCK_DIV_MASK;
+        value |= (n << CLOCK_CNT_LOW_SHIFT) & CLOCK_CNT_LOW_MASK;
+        value |= (((n + 1) / 2 - 1) << CLOCK_CNT_HIGH_SHIFT) &
+                CLOCK_CNT_HIGH_MASK;
+
+        regmap_write(spifc->regmap, REG_CLOCK, value);
+}
+
+/**
+ * meson_spifc_txrx() - transfer a chunk of data
+ * @spifc:      the Meson SPI device
+ * @xfer:       the current SPI transfer
+ * @offset:     offset of the data to transfer
+ * @len:        length of the data to transfer
+ * @last_xfer:  whether this is the last transfer of the message
+ * @last_chunk: whether this is the last chunk of the transfer
+ * Return:      0 on success, a negative value on error
+ */
+static int meson_spifc_txrx(struct meson_spifc *spifc,
+                            struct spi_transfer *xfer,
+                            int offset, int len, bool last_xfer,
+                            bool last_chunk)
+{
+        bool keep_cs = true;
+        int ret;
+
+        if (xfer->tx_buf)
+                meson_spifc_fill_buffer(spifc, xfer->tx_buf + offset, len);
+
+        /* enable DOUT stage */
+        regmap_update_bits(spifc->regmap, REG_USER, USER_UC_MASK,
+                           USER_UC_DOUT_SEL);
+        regmap_write(spifc->regmap, REG_USER1,
+                     (8 * len - 1) << USER1_BN_UC_DOUT_SHIFT);
+
+        /* enable data input during DOUT */
+        regmap_update_bits(spifc->regmap, REG_USER, USER_DIN_EN_MS,
+                           USER_DIN_EN_MS);
+
+        if (last_chunk) {
+                if (last_xfer)
+                        keep_cs = xfer->cs_change;
+                else
+                        keep_cs = !xfer->cs_change;
+        }
+
+        regmap_update_bits(spifc->regmap, REG_USER4, USER4_CS_ACT,
+                           keep_cs ? USER4_CS_ACT : 0);
+
+        /* clear transition done bit */
+        regmap_update_bits(spifc->regmap, REG_SLAVE, SLAVE_TRST_DONE, 0);
+        /* start transfer */
+        regmap_update_bits(spifc->regmap, REG_CMD, CMD_USER, CMD_USER);
+
+        ret = meson_spifc_wait_ready(spifc);
+
+        if (!ret && xfer->rx_buf)
+                meson_spifc_drain_buffer(spifc, xfer->rx_buf + offset, len);
+
+        return ret;
+}
+
+/**
+ * meson_spifc_transfer_one() - perform a single transfer
+ * @master:     the SPI master
+ * @spi:        the SPI device
+ * @xfer:       the current SPI transfer
+ * Return:      0 on success, a negative value on error
+ */
+static int meson_spifc_transfer_one(struct spi_master *master,
+                                    struct spi_device *spi,
+                                    struct spi_transfer *xfer)
+{
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+        int len, done = 0, ret = 0;
+
+        meson_spifc_setup_speed(spifc, xfer->speed_hz);
+
+        regmap_update_bits(spifc->regmap, REG_CTRL, CTRL_ENABLE_AHB, 0);
+
+        while (done < xfer->len && !ret) {
+                len = min_t(int, xfer->len - done, SPIFC_BUFFER_SIZE);
+                ret = meson_spifc_txrx(spifc, xfer, done, len,
+                                       spi_transfer_is_last(master, xfer),
+                                       done + len >= xfer->len);
+                done += len;
+        }
+
+        regmap_update_bits(spifc->regmap, REG_CTRL, CTRL_ENABLE_AHB,
+                           CTRL_ENABLE_AHB);
+
+        return ret;
+}
+
+/**
+ * meson_spifc_hw_init() - reset and initialize the SPI controller
+ * @spifc:      the Meson SPI device
+ */
+static void meson_spifc_hw_init(struct meson_spifc *spifc)
+{
+        /* reset device */
+        regmap_update_bits(spifc->regmap, REG_SLAVE, SLAVE_SW_RST,
+                           SLAVE_SW_RST);
+        /* disable compatible mode */
+        regmap_update_bits(spifc->regmap, REG_USER, USER_CMP_MODE, 0);
+        /* set master mode */
+        regmap_update_bits(spifc->regmap, REG_SLAVE, SLAVE_OP_MODE, 0);
+}
+
+static int meson_spifc_probe(struct platform_device *pdev)
+{
+        struct spi_master *master;
+        struct meson_spifc *spifc;
+        struct resource *res;
+        void __iomem *base;
+        unsigned int rate;
+        int ret = 0;
+
+        master = spi_alloc_master(&pdev->dev, sizeof(struct meson_spifc));
+        if (!master)
+                return -ENOMEM;
+
+        platform_set_drvdata(pdev, master);
+
+        spifc = spi_master_get_devdata(master);
+        spifc->dev = &pdev->dev;
+
+        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        base = devm_ioremap_resource(spifc->dev, res);
+        if (IS_ERR(base)) {
+                ret = PTR_ERR(base);
+                goto out_err;
+        }
+
+        spifc->regmap = devm_regmap_init_mmio(spifc->dev, base,
+                                              &spifc_regmap_config);
+        if (IS_ERR(spifc->regmap)) {
+                ret = PTR_ERR(spifc->regmap);
+                goto out_err;
+        }
+
+        spifc->clk = devm_clk_get(spifc->dev, NULL);
+        if (IS_ERR(spifc->clk)) {
+                dev_err(spifc->dev, "missing clock\n");
+                ret = PTR_ERR(spifc->clk);
+                goto out_err;
+        }
+
+        ret = clk_prepare_enable(spifc->clk);
+        if (ret) {
+                dev_err(spifc->dev, "can't prepare clock\n");
+                goto out_err;
+        }
+
+        rate = clk_get_rate(spifc->clk);
+
+        master->num_chipselect = 1;
+        master->dev.of_node = pdev->dev.of_node;
+        master->bits_per_word_mask = SPI_BPW_MASK(8);
+        master->auto_runtime_pm = true;
+        master->transfer_one = meson_spifc_transfer_one;
+        master->min_speed_hz = rate >> 6;
+        master->max_speed_hz = rate >> 1;
+
+        meson_spifc_hw_init(spifc);
+
+        pm_runtime_set_active(spifc->dev);
+        pm_runtime_enable(spifc->dev);
+
+        ret = devm_spi_register_master(spifc->dev, master);
+        if (ret) {
+                dev_err(spifc->dev, "failed to register spi master\n");
+                goto out_clk;
+        }
+
+        return 0;
+out_clk:
+        clk_disable_unprepare(spifc->clk);
+out_err:
+        spi_master_put(master);
+        return ret;
+}
+
+static int meson_spifc_remove(struct platform_device *pdev)
+{
+        struct spi_master *master = platform_get_drvdata(pdev);
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+
+        pm_runtime_get_sync(&pdev->dev);
+        clk_disable_unprepare(spifc->clk);
+        pm_runtime_disable(&pdev->dev);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int meson_spifc_suspend(struct device *dev)
+{
+        struct spi_master *master = dev_get_drvdata(dev);
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+        int ret;
+
+        ret = spi_master_suspend(master);
+        if (ret)
+                return ret;
+
+        if (!pm_runtime_suspended(dev))
+                clk_disable_unprepare(spifc->clk);
+
+        return 0;
+}
+
+static int meson_spifc_resume(struct device *dev)
+{
+        struct spi_master *master = dev_get_drvdata(dev);
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+        int ret;
+
+        if (!pm_runtime_suspended(dev)) {
+                ret = clk_prepare_enable(spifc->clk);
+                if (ret)
+                        return ret;
+        }
+
+        meson_spifc_hw_init(spifc);
+
+        ret = spi_master_resume(master);
+        if (ret)
+                clk_disable_unprepare(spifc->clk);
+
+        return ret;
+}
+#endif /* CONFIG_PM_SLEEP */
+
+#ifdef CONFIG_PM_RUNTIME
+static int meson_spifc_runtime_suspend(struct device *dev)
+{
+        struct spi_master *master = dev_get_drvdata(dev);
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+
+        clk_disable_unprepare(spifc->clk);
+
+        return 0;
+}
+
+static int meson_spifc_runtime_resume(struct device *dev)
+{
+        struct spi_master *master = dev_get_drvdata(dev);
+        struct meson_spifc *spifc = spi_master_get_devdata(master);
+
+        return clk_prepare_enable(spifc->clk);
+}
+#endif /* CONFIG_PM_RUNTIME */
+
+static const struct dev_pm_ops meson_spifc_pm_ops = {
+        SET_SYSTEM_SLEEP_PM_OPS(meson_spifc_suspend, meson_spifc_resume)
+        SET_RUNTIME_PM_OPS(meson_spifc_runtime_suspend,
+                           meson_spifc_runtime_resume,
+                           NULL)
+};
+
+static const struct of_device_id meson_spifc_dt_match[] = {
+        { .compatible = "amlogic,meson6-spifc", },
+        { },
+};
+
+static struct platform_driver meson_spifc_driver = {
+        .probe  = meson_spifc_probe,
+        .remove = meson_spifc_remove,
+        .driver = {
+                .name           = "meson-spifc",
+                .of_match_table = of_match_ptr(meson_spifc_dt_match),
+                .pm             = &meson_spifc_pm_ops,
+        },
+};
+
+module_platform_driver(meson_spifc_driver);
+
+MODULE_AUTHOR("Beniamino Galvani <b.galvani@gmail.com>");
+MODULE_DESCRIPTION("Amlogic Meson SPIFC driver");
+MODULE_LICENSE("GPL v2");