Hi Longbin: On 18:12 Mon 24 Feb , Longbin Li wrote: > Add support for Sophgo SPI NOR controller in Sophgo SoC. > > Signed-off-by: Longbin Li <looong.bin@xxxxxxxxx> > --- > drivers/spi/Kconfig | 9 + > drivers/spi/Makefile | 1 + > drivers/spi/spi-sophgo-nor.c | 501 +++++++++++++++++++++++++++++++++++ > 3 files changed, 511 insertions(+) > create mode 100644 drivers/spi/spi-sophgo-nor.c > > diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig > index ea8a31032927..6b6d7b348485 100644 > --- a/drivers/spi/Kconfig > +++ b/drivers/spi/Kconfig > @@ -1021,6 +1021,15 @@ config SPI_SN_F_OSPI > for connecting an SPI Flash memory over up to 8-bit wide bus. > It supports indirect access mode only. > > +config SPI_SOPHGO_NOR > + tristate "Sophgo SPI NOR Controller" > + depends on ARCH_SOPHGO || COMPILE_TEST > + help > + This enables support for the Sophgo SPI NOR controller, > + which supports Dual/Qual read and write operations while > + also supporting 3Byte address devices and 4Byte address > + devices. > + > config SPI_SPRD > tristate "Spreadtrum SPI controller" > depends on ARCH_SPRD || COMPILE_TEST > diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile > index 9db7554c1864..9ded1de4b2fd 100644 > --- a/drivers/spi/Makefile > +++ b/drivers/spi/Makefile > @@ -134,6 +134,7 @@ obj-$(CONFIG_SPI_SH_SCI) += spi-sh-sci.o > obj-$(CONFIG_SPI_SIFIVE) += spi-sifive.o > obj-$(CONFIG_SPI_SLAVE_MT27XX) += spi-slave-mt27xx.o > obj-$(CONFIG_SPI_SN_F_OSPI) += spi-sn-f-ospi.o > +obj-$(CONFIG_SPI_SOPHGO_NOR) += spi-sophgo-nor.o > obj-$(CONFIG_SPI_SPRD) += spi-sprd.o > obj-$(CONFIG_SPI_SPRD_ADI) += spi-sprd-adi.o > obj-$(CONFIG_SPI_STM32) += spi-stm32.o > diff --git a/drivers/spi/spi-sophgo-nor.c b/drivers/spi/spi-sophgo-nor.c > new file mode 100644 > index 000000000000..1139deeac327 > --- /dev/null > +++ b/drivers/spi/spi-sophgo-nor.c > @@ -0,0 +1,501 @@ > +// SPDX-License-Identifier: GPL-2.0-only > +/* > + * Sophgo SPI NOR controller driver > + * > + * Copyright (c) 2025 Longbin Li <looong.bin@xxxxxxxxx> > + */ > + > +#include <linux/bitfield.h> > +#include <linux/clk.h> > +#include <linux/iopoll.h> > +#include <linux/module.h> > +#include <linux/of.h> > +#include <linux/platform_device.h> > +#include <linux/spi/spi-mem.h> > + > +/* Hardware register definitions */ > +#define SPIFMC_CTRL 0x00 > +#define SPIFMC_CTRL_CPHA BIT(12) > +#define SPIFMC_CTRL_CPOL BIT(13) > +#define SPIFMC_CTRL_HOLD_OL BIT(14) > +#define SPIFMC_CTRL_WP_OL BIT(15) > +#define SPIFMC_CTRL_LSBF BIT(20) > +#define SPIFMC_CTRL_SRST BIT(21) > +#define SPIFMC_CTRL_SCK_DIV_SHIFT 0 > +#define SPIFMC_CTRL_FRAME_LEN_SHIFT 16 > +#define SPIFMC_CTRL_SCK_DIV_MASK 0x7FF > + > +#define SPIFMC_CE_CTRL 0x04 > +#define SPIFMC_CE_CTRL_CEMANUAL BIT(0) > +#define SPIFMC_CE_CTRL_CEMANUAL_EN BIT(1) > + > +#define SPIFMC_DLY_CTRL 0x08 > +#define SPIFMC_CTRL_FM_INTVL_MASK 0x000f > +#define SPIFMC_CTRL_FM_INTVL BIT(0) > +#define SPIFMC_CTRL_CET_MASK 0x0f00 > +#define SPIFMC_CTRL_CET BIT(8) > + > +#define SPIFMC_DMMR 0x0c > + > +#define SPIFMC_TRAN_CSR 0x10 > +#define SPIFMC_TRAN_CSR_TRAN_MODE_MASK GENMASK(1, 0) > +#define SPIFMC_TRAN_CSR_TRAN_MODE_RX BIT(0) > +#define SPIFMC_TRAN_CSR_TRAN_MODE_TX BIT(1) > +#define SPIFMC_TRAN_CSR_FAST_MODE BIT(3) > +#define SPIFMC_TRAN_CSR_BUS_WIDTH_1_BIT (0x00 << 4) > +#define SPIFMC_TRAN_CSR_BUS_WIDTH_2_BIT (0x01 << 4) > +#define SPIFMC_TRAN_CSR_BUS_WIDTH_4_BIT (0x02 << 4) > +#define SPIFMC_TRAN_CSR_DMA_EN BIT(6) > +#define SPIFMC_TRAN_CSR_MISO_LEVEL BIT(7) > +#define SPIFMC_TRAN_CSR_ADDR_BYTES_MASK GENMASK(10, 8) > +#define SPIFMC_TRAN_CSR_ADDR_BYTES_SHIFT 8 > +#define SPIFMC_TRAN_CSR_WITH_CMD BIT(11) > +#define SPIFMC_TRAN_CSR_FIFO_TRG_LVL_MASK GENMASK(13, 12) > +#define SPIFMC_TRAN_CSR_FIFO_TRG_LVL_1_BYTE (0x00 << 12) > +#define SPIFMC_TRAN_CSR_FIFO_TRG_LVL_2_BYTE (0x01 << 12) > +#define SPIFMC_TRAN_CSR_FIFO_TRG_LVL_4_BYTE (0x02 << 12) > +#define SPIFMC_TRAN_CSR_FIFO_TRG_LVL_8_BYTE (0x03 << 12) > +#define SPIFMC_TRAN_CSR_GO_BUSY BIT(15) > +#define SPIFMC_TRAN_CSR_ADDR4B_SHIFT 20 > +#define SPIFMC_TRAN_CSR_CMD4B_SHIFT 21 > + > +#define SPIFMC_TRAN_NUM 0x14 > +#define SPIFMC_FIFO_PORT 0x18 > +#define SPIFMC_FIFO_PT 0x20 > + > +#define SPIFMC_INT_STS 0x28 > +#define SPIFMC_INT_TRAN_DONE BIT(0) > +#define SPIFMC_INT_RD_FIFO BIT(2) > +#define SPIFMC_INT_WR_FIFO BIT(3) > +#define SPIFMC_INT_RX_FRAME BIT(4) > +#define SPIFMC_INT_TX_FRAME BIT(5) > + > +#define SPIFMC_INT_EN 0x2c > +#define SPIFMC_INT_TRAN_DONE_EN BIT(0) > +#define SPIFMC_INT_RD_FIFO_EN BIT(2) > +#define SPIFMC_INT_WR_FIFO_EN BIT(3) > +#define SPIFMC_INT_RX_FRAME_EN BIT(4) > +#define SPIFMC_INT_TX_FRAME_EN BIT(5) > + > +#define SPIFMC_OPT 0x030 > +#define SPIFMC_OPT_DISABLE_FIFO_FLUSH BIT(1) > + > +#define SPIFMC_MAX_FIFO_DEPTH 8 > + > +#define SPIFMC_MAX_READ_SIZE 0x10000 > + > +struct sophgo_spifmc { > + struct spi_controller *ctrl; > + void __iomem *io_base; > + struct device *dev; > + struct mutex lock; it will be great to document the lock > + struct clk *clk; > +}; > + > +static int sophgo_spifmc_wait_int(struct sophgo_spifmc *spifmc, u8 int_type) > +{ > + u32 stat; > + > + return readl_poll_timeout(spifmc->io_base + SPIFMC_INT_STS, stat, > + (stat & int_type), 0, 1000000); > +} > + > +static int sophgo_spifmc_wait_xfer_size(struct sophgo_spifmc *spifmc, > + int xfer_size) > +{ > + u8 stat; > + > + return readl_poll_timeout(spifmc->io_base + SPIFMC_FIFO_PT, stat, > + ((stat & 0xf) == xfer_size), 1, 1000000); > +} > + > +static u32 sophgo_spifmc_init_reg(struct sophgo_spifmc *spifmc) > +{ > + u32 reg; > + > + reg = readl(spifmc->io_base + SPIFMC_TRAN_CSR); > + reg &= ~(SPIFMC_TRAN_CSR_TRAN_MODE_MASK | > + SPIFMC_TRAN_CSR_FAST_MODE | > + SPIFMC_TRAN_CSR_BUS_WIDTH_2_BIT | > + SPIFMC_TRAN_CSR_BUS_WIDTH_4_BIT | > + SPIFMC_TRAN_CSR_DMA_EN | > + SPIFMC_TRAN_CSR_ADDR_BYTES_MASK | > + SPIFMC_TRAN_CSR_WITH_CMD | > + SPIFMC_TRAN_CSR_FIFO_TRG_LVL_MASK); > + > + writel(reg, spifmc->io_base + SPIFMC_TRAN_CSR); > + > + return reg; > +} > + > +static ssize_t sophgo_spifmc_read_64k(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op, loff_t from, > + size_t len, u_char *buf) > +{ > + int xfer_size, offset; > + u32 reg; > + int ret; > + int i; > + > + reg = sophgo_spifmc_init_reg(spifmc); > + reg |= (op->addr.nbytes + op->dummy.nbytes) << SPIFMC_TRAN_CSR_ADDR_BYTES_SHIFT; > + reg |= SPIFMC_TRAN_CSR_FIFO_TRG_LVL_8_BYTE; > + reg |= SPIFMC_TRAN_CSR_WITH_CMD; > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_RX; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + writeb(op->cmd.opcode, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = op->addr.nbytes - 1; i >= 0; i--) > + writeb((from >> i * 8) & 0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = 0; i < op->dummy.nbytes; i++) > + writeb(0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + writel(len, spifmc->io_base + SPIFMC_TRAN_NUM); > + writel(0, spifmc->io_base + SPIFMC_INT_STS); > + reg |= SPIFMC_TRAN_CSR_GO_BUSY; > + writel(reg, spifmc->io_base + SPIFMC_TRAN_CSR); > + > + ret = sophgo_spifmc_wait_int(spifmc, SPIFMC_INT_RD_FIFO); > + if (ret < 0) > + return ret; > + > + offset = 0; > + while (offset < len) { > + xfer_size = min_t(size_t, SPIFMC_MAX_FIFO_DEPTH, len - offset); > + > + ret = sophgo_spifmc_wait_xfer_size(spifmc, xfer_size); > + if (ret < 0) > + return ret; > + > + for (i = 0; i < xfer_size; i++) > + buf[i + offset] = readb(spifmc->io_base + SPIFMC_FIFO_PORT); > + > + offset += xfer_size; > + } > + > + ret = sophgo_spifmc_wait_int(spifmc, SPIFMC_INT_TRAN_DONE); > + if (ret < 0) > + return ret; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + > + return len; > +} > + > +static ssize_t sophgo_spifmc_read(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op) > +{ > + size_t xfer_size; > + size_t offset; > + loff_t from = op->addr.val; > + size_t len = op->data.nbytes; > + int ret; > + u8 *din = op->data.buf.in; > + > + offset = 0; > + while (offset < len) { > + xfer_size = min_t(size_t, SPIFMC_MAX_READ_SIZE, len - offset); > + > + ret = sophgo_spifmc_read_64k(spifmc, op, from, xfer_size, din); > + if (ret < 0) > + return ret; > + > + offset += xfer_size; > + din += xfer_size; > + from += xfer_size; > + } > + > + return 0; > +} > + > +static ssize_t sophgo_spifmc_write(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op) > +{ > + size_t xfer_size; > + const u8 *dout = op->data.buf.out; > + int i, offset; > + size_t ret; > + u32 reg; > + > + reg = sophgo_spifmc_init_reg(spifmc); > + reg |= (op->addr.nbytes + op->dummy.nbytes) << SPIFMC_TRAN_CSR_ADDR_BYTES_SHIFT; > + reg |= SPIFMC_TRAN_CSR_FIFO_TRG_LVL_8_BYTE; > + reg |= SPIFMC_TRAN_CSR_WITH_CMD; > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_TX; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + writeb(op->cmd.opcode, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = op->addr.nbytes - 1; i >= 0; i--) > + writeb((op->addr.val >> i * 8) & 0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = 0; i < op->dummy.nbytes; i++) > + writeb(0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + writel(0, spifmc->io_base + SPIFMC_INT_STS); > + writel(op->data.nbytes, spifmc->io_base + SPIFMC_TRAN_NUM); > + reg |= SPIFMC_TRAN_CSR_GO_BUSY; > + writel(reg, spifmc->io_base + SPIFMC_TRAN_CSR); > + > + ret = sophgo_spifmc_wait_xfer_size(spifmc, 0); > + if (ret < 0) > + return ret; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + > + offset = 0; > + while (offset < op->data.nbytes) { > + xfer_size = min_t(size_t, SPIFMC_MAX_FIFO_DEPTH, op->data.nbytes - offset); > + > + ret = sophgo_spifmc_wait_xfer_size(spifmc, 0); > + if (ret < 0) > + return ret; > + > + for (i = 0; i < xfer_size; i++) > + writeb(dout[i + offset], spifmc->io_base + SPIFMC_FIFO_PORT); > + > + offset += xfer_size; > + } > + > + ret = sophgo_spifmc_wait_int(spifmc, SPIFMC_INT_TRAN_DONE); > + if (ret < 0) > + return ret; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + > + return 0; > +} > + > +static ssize_t sophgo_spifmc_tran_cmd(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op) > +{ > + int i, ret; > + u32 reg; > + > + reg = sophgo_spifmc_init_reg(spifmc); > + reg |= (op->addr.nbytes + op->dummy.nbytes) << SPIFMC_TRAN_CSR_ADDR_BYTES_SHIFT; > + reg |= SPIFMC_TRAN_CSR_FIFO_TRG_LVL_1_BYTE; > + reg |= SPIFMC_TRAN_CSR_WITH_CMD; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + writeb(op->cmd.opcode, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = op->addr.nbytes - 1; i >= 0; i--) > + writeb((op->addr.val >> i * 8) & 0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = 0; i < op->dummy.nbytes; i++) > + writeb(0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + writel(0, spifmc->io_base + SPIFMC_INT_STS); > + reg |= SPIFMC_TRAN_CSR_GO_BUSY; > + writel(reg, spifmc->io_base + SPIFMC_TRAN_CSR); > + > + ret = sophgo_spifmc_wait_int(spifmc, SPIFMC_INT_TRAN_DONE); > + if (ret < 0) > + return ret; > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + > + return 0; > +} > + > +static void sophgo_spifmc_trans(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op) > +{ > + if (op->data.dir == SPI_MEM_DATA_IN) > + sophgo_spifmc_read(spifmc, op); > + else if (op->data.dir == SPI_MEM_DATA_OUT) > + sophgo_spifmc_write(spifmc, op); > + else > + sophgo_spifmc_tran_cmd(spifmc, op); > +} > + > +static ssize_t sophgo_spifmc_trans_reg(struct sophgo_spifmc *spifmc, > + const struct spi_mem_op *op) > +{ > + const u8 *dout = NULL; > + u8 *din = NULL; > + size_t len = op->data.nbytes; > + u32 reg; > + int ret; > + int i; squash them which save one line: int i, ret; > + > + if (op->data.dir == SPI_MEM_DATA_IN) > + din = op->data.buf.in; > + else > + dout = op->data.buf.out; > + > + reg = sophgo_spifmc_init_reg(spifmc); > + reg |= SPIFMC_TRAN_CSR_FIFO_TRG_LVL_1_BYTE; > + reg |= SPIFMC_TRAN_CSR_WITH_CMD; > + > + if (din) { > + reg |= SPIFMC_TRAN_CSR_BUS_WIDTH_1_BIT; > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_RX; > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_TX; > + > + writel(SPIFMC_OPT_DISABLE_FIFO_FLUSH, spifmc->io_base + SPIFMC_OPT); > + } else { > + /* > + * If write values to the Status Register, > + * configure TRAN_CSR register as the same as > + * sophgo_spifmc_read_reg. > + */ > + if (op->cmd.opcode == 0x01) { > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_RX; > + reg |= SPIFMC_TRAN_CSR_TRAN_MODE_TX; > + writel(len, spifmc->io_base + SPIFMC_TRAN_NUM); > + } > + } > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + writeb(op->cmd.opcode, spifmc->io_base + SPIFMC_FIFO_PORT); > + > + for (i = 0; i < len; i++) { > + if (din) > + writeb(0xff, spifmc->io_base + SPIFMC_FIFO_PORT); > + else > + writeb(dout[i], spifmc->io_base + SPIFMC_FIFO_PORT); > + } > + > + writel(0, spifmc->io_base + SPIFMC_INT_STS); > + writel(len, spifmc->io_base + SPIFMC_TRAN_NUM); > + reg |= SPIFMC_TRAN_CSR_GO_BUSY; > + writel(reg, spifmc->io_base + SPIFMC_TRAN_CSR); > + > + ret = sophgo_spifmc_wait_int(spifmc, SPIFMC_INT_TRAN_DONE); > + if (ret < 0) > + return ret; > + > + if (din) { > + while (len--) > + *din++ = readb(spifmc->io_base + SPIFMC_FIFO_PORT); > + } > + > + writel(0, spifmc->io_base + SPIFMC_FIFO_PT); > + > + return 0; > +} > + > +static int sophgo_spifmc_exec_op(struct spi_mem *mem, > + const struct spi_mem_op *op) > +{ > + struct sophgo_spifmc *spifmc; > + > + spifmc = spi_controller_get_devdata(mem->spi->controller); > + > + mutex_lock(&spifmc->lock); > + > + if (op->addr.nbytes == 0) > + sophgo_spifmc_trans_reg(spifmc, op); > + else > + sophgo_spifmc_trans(spifmc, op); > + > + mutex_unlock(&spifmc->lock); > + > + return 0; > +} > + > +static const struct spi_controller_mem_ops sophgo_spifmc_mem_ops = { > + .exec_op = sophgo_spifmc_exec_op, > +}; > + > +static void sophgo_spifmc_init(struct sophgo_spifmc *spifmc) > +{ > + u32 tran_csr; > + u32 reg; > + > + writel(0, spifmc->io_base + SPIFMC_DMMR); > + > + reg = readl(spifmc->io_base + SPIFMC_CTRL); > + reg |= SPIFMC_CTRL_SRST; .. > + reg &= ~((1 << 11) - 1); so this is a mask? use macro to define, instead of using magic number > + reg |= 1; > + writel(reg, spifmc->io_base + SPIFMC_CTRL); > + > + writel(0, spifmc->io_base + SPIFMC_CE_CTRL); > + > + tran_csr = readl(spifmc->io_base + SPIFMC_TRAN_CSR); > + tran_csr |= (0 << SPIFMC_TRAN_CSR_ADDR_BYTES_SHIFT); > + tran_csr |= SPIFMC_TRAN_CSR_FIFO_TRG_LVL_4_BYTE; > + tran_csr |= SPIFMC_TRAN_CSR_WITH_CMD; > + writel(tran_csr, spifmc->io_base + SPIFMC_TRAN_CSR); > +} > + > +static int sophgo_spifmc_probe(struct platform_device *pdev) > +{ > + struct spi_controller *ctrl; > + struct sophgo_spifmc *spifmc; > + void __iomem *base; > + int ret; > + > + ctrl = devm_spi_alloc_host(&pdev->dev, sizeof(*spifmc)); > + if (!ctrl) > + return -ENOMEM; > + > + spifmc = spi_controller_get_devdata(ctrl); > + dev_set_drvdata(&pdev->dev, ctrl); > + .. > + spifmc->clk = devm_clk_get(&pdev->dev, NULL); > + if (IS_ERR(spifmc->clk)) { > + dev_err(&pdev->dev, "AHB clock not found.\n"); > + return PTR_ERR(spifmc->clk); > + } > + > + ret = clk_prepare_enable(spifmc->clk); > + if (ret) { > + dev_err(&pdev->dev, "Unable to enable AHB clock.\n"); > + return ret; > + } you can combine above with devm_clk_get_enabled(), and simplify return routine by using "return dev_err_probe(..)" > + > + spifmc->dev = &pdev->dev; > + spifmc->ctrl = ctrl; > + > + spifmc->io_base = devm_platform_ioremap_resource(pdev, 0); > + if (IS_ERR(base)) > + return PTR_ERR(base); > + > + ctrl->num_chipselect = 1; > + ctrl->dev.of_node = pdev->dev.of_node; > + ctrl->bits_per_word_mask = SPI_BPW_MASK(8); > + ctrl->auto_runtime_pm = false; > + ctrl->mem_ops = &sophgo_spifmc_mem_ops; > + ctrl->mode_bits = SPI_RX_DUAL | SPI_TX_DUAL | SPI_RX_QUAD | SPI_TX_QUAD; > + > + mutex_init(&spifmc->lock); strictly, you still need to do error handler, e.g, destroy mutex if probe fail > + > + sophgo_spifmc_init(spifmc); > + sophgo_spifmc_init_reg(spifmc); > + > + return devm_spi_register_controller(&pdev->dev, ctrl); > +} > + > +static void sophgo_spifmc_remove(struct platform_device *pdev) > +{ > + struct sophgo_spifmc *spifmc = platform_get_drvdata(pdev); > + > + mutex_destroy(&spifmc->lock); > +} > + > +static const struct of_device_id sophgo_spifmc_match[] = { > + { .compatible = "sophgo,sg2044-spifmc-nor" }, > + { /* sentinel */ } > +}; > +MODULE_DEVICE_TABLE(of, sophgo_spifmc_match); > + > +static struct platform_driver sophgo_nor_driver = { > + .driver = { > + .name = "sophgo,spifmc-nor", > + .of_match_table = sophgo_spifmc_match, > + }, > + .probe = sophgo_spifmc_probe, > + .remove = sophgo_spifmc_remove, > +}; .. > + spurious blank line here, drop it > +module_platform_driver(sophgo_nor_driver); > + > +MODULE_DESCRIPTION("Sophgo SPI NOR controller driver"); > +MODULE_AUTHOR("Longbin Li <looong.bin@xxxxxxxxx>"); > +MODULE_LICENSE("GPL"); > -- > 2.48.1 -- Yixun Lan (dlan) Gentoo Linux Developer GPG Key ID AABEFD55