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SubjectRe: [PATCH V4 3/4] spi: spi-geni-qcom: Add SPI driver support for GENI based QUP
Date
Quoting Dilip Kota (2018-09-18 11:07:25)
> diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
> new file mode 100644
> index 0000000..949b853
> --- /dev/null
> +++ b/drivers/spi/spi-geni-qcom.c
> @@ -0,0 +1,653 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
> +
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/log2.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/qcom-geni-se.h>
> +#include <linux/spi/spi.h>
> +#include <linux/spinlock.h>
> +
> +/* SPI SE specific registers and respective register fields */
> +#define SE_SPI_CPHA 0x224
> +#define CPHA BIT(0)
> +
> +#define SE_SPI_LOOPBACK 0x22c
> +#define LOOPBACK_ENABLE 0x1
> +#define NORMAL_MODE 0x0
> +#define LOOPBACK_MSK GENMASK(1, 0)
> +
> +#define SE_SPI_CPOL 0x230
> +#define CPOL BIT(2)
> +
> +#define SE_SPI_DEMUX_OUTPUT_INV 0x24c
> +#define CS_DEMUX_OUTPUT_INV_MSK GENMASK(3, 0)
> +
> +#define SE_SPI_DEMUX_SEL 0x250
> +#define CS_DEMUX_OUTPUT_SEL GENMASK(3, 0)
> +
> +#define SE_SPI_TRANS_CFG 0x25c
> +#define CS_TOGGLE BIT(0)
> +
> +#define SE_SPI_WORD_LEN 0x268
> +#define WORD_LEN_MSK GENMASK(9, 0)
> +#define MIN_WORD_LEN 4
> +
> +#define SE_SPI_TX_TRANS_LEN 0x26c
> +#define SE_SPI_RX_TRANS_LEN 0x270
> +#define TRANS_LEN_MSK GENMASK(23, 0)
> +
> +#define SE_SPI_PRE_POST_CMD_DLY 0x274
> +
> +#define SE_SPI_DELAY_COUNTERS 0x278
> +#define SPI_INTER_WORDS_DELAY_MSK GENMASK(9, 0)
> +#define SPI_CS_CLK_DELAY_MSK GENMASK(19, 10)
> +#define SPI_CS_CLK_DELAY_SHFT 10
> +
> +/* M_CMD OP codes for SPI */
> +#define SPI_TX_ONLY 1
> +#define SPI_RX_ONLY 2
> +#define SPI_FULL_DUPLEX 3
> +#define SPI_TX_RX 7
> +#define SPI_CS_ASSERT 8
> +#define SPI_CS_DEASSERT 9
> +#define SPI_SCK_ONLY 10
> +/* M_CMD params for SPI */
> +#define SPI_PRE_CMD_DELAY BIT(0)
> +#define TIMESTAMP_BEFORE BIT(1)
> +#define FRAGMENTATION BIT(2)
> +#define TIMESTAMP_AFTER BIT(3)
> +#define POST_CMD_DELAY BIT(4)
> +
> +static irqreturn_t geni_spi_isr(int irq, void *data);

Does this need to be forward declared?

> +
> +struct spi_geni_master {
> + struct geni_se se;
> + struct device *dev;
> + u32 rx_fifo_depth;

Is this used?

> + u32 tx_fifo_depth;
> + u32 fifo_width_bits;
> + u32 tx_wm;
> + unsigned int cur_speed_hz;

unsigned long for Hz? The clk framework uses that type.

> + unsigned int cur_bits_per_word;
> + unsigned int tx_rem_bytes;
> + unsigned int rx_rem_bytes;
> + struct spi_transfer *cur_xfer;

const?

> + struct completion xfer_done;
> + unsigned int oversampling;
> + spinlock_t lock;
> +};
> +
[...]
> +
> +static int spi_geni_prepare_message(struct spi_master *spi,
> + struct spi_message *spi_msg)
> +{
> + int ret;
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> + struct geni_se *se = &mas->se;
> +
> + geni_se_select_mode(se, GENI_SE_FIFO);
> + reinit_completion(&mas->xfer_done);
> + ret = setup_fifo_params(spi_msg->spi, spi);
> + if (ret)
> + dev_err(mas->dev, "Couldn't select mode %d", ret);

Missing newline on error print.

> + return ret;
> +}
> +
[...]
> +
> +static void setup_fifo_xfer(struct spi_transfer *xfer,
> + struct spi_geni_master *mas,
> + u16 mode, struct spi_master *spi)
> +{
> + u32 m_cmd = 0, m_param = 0;
> + u32 spi_tx_cfg, trans_len;
> + struct geni_se *se = &mas->se;
> +
> + spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG);
> + if (xfer->bits_per_word != mas->cur_bits_per_word) {
> + spi_setup_word_len(mas, mode, xfer->bits_per_word);
> + mas->cur_bits_per_word = xfer->bits_per_word;
> + }
> +
> + /* Speed and bits per word can be overridden per transfer */
> + if (xfer->speed_hz != mas->cur_speed_hz) {
> + int ret;
> + u32 clk_sel, m_clk_cfg;
> + unsigned int idx, div;
> +
> + ret = get_spi_clk_cfg(xfer->speed_hz, mas, &idx, &div);
> + if (ret) {
> + dev_err(mas->dev, "Err setting clks:%d\n", ret);
> + return;
> + }
> + /*
> + * SPI core clock gets configured with the requested frequency
> + * or the frequency closer to the requested frequency.
> + * For that reason requested frequency is stored in the
> + * cur_speed_hz and referred in the consicutive transfer instead

s/consicutive/consecutive/

> + * of calling clk_get_rate() API.
> + */
> + mas->cur_speed_hz = xfer->speed_hz;
> + clk_sel = idx & CLK_SEL_MSK;
> + m_clk_cfg = (div << CLK_DIV_SHFT) | SER_CLK_EN;
> + writel(clk_sel, se->base + SE_GENI_CLK_SEL);
> + writel(m_clk_cfg, se->base + GENI_SER_M_CLK_CFG);
> + }
> +
> + mas->tx_rem_bytes = 0;
> + mas->rx_rem_bytes = 0;
> + if (xfer->tx_buf && xfer->rx_buf)
> + m_cmd = SPI_FULL_DUPLEX;
> + else if (xfer->tx_buf)
> + m_cmd = SPI_TX_ONLY;
> + else if (xfer->rx_buf)
> + m_cmd = SPI_RX_ONLY;
> +
> + spi_tx_cfg &= ~CS_TOGGLE;
> + if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
> + trans_len =
> + (xfer->len * BITS_PER_BYTE /
> + mas->cur_bits_per_word) & TRANS_LEN_MSK;
> + } else {
> + unsigned int bytes_per_word =
> + mas->cur_bits_per_word / BITS_PER_BYTE + 1;
> +
> + trans_len = (xfer->len / bytes_per_word) & TRANS_LEN_MSK;
> + }

Rename 'trans_len' to 'len' and shorten some lines by taking out the
mask to get:

if (!(mas->cur_bits_per_word % MIN_WORD_LEN))
len = xfer->len * BITS_PER_BYTE / mas->cur_bits_per_word
else
len = xfer->len / (mas->cur_bits_per_word / BITS_PER_BYTE + 1);
len &= TRANS_LEN_MSK;

> +
> + /*
> + * If CS change flag is set, then toggle the CS line in between
> + * transfers and keep CS asserted after the last transfer.
> + * Else if keep CS flag asserted in between transfers and de-assert
> + * CS after the last message.
> + */
> + if (xfer->cs_change) {
> + if (list_is_last(&xfer->transfer_list,
> + &spi->cur_msg->transfers))
> + m_param = FRAGMENTATION;
> + } else {
> + if (!list_is_last(&xfer->transfer_list,
> + &spi->cur_msg->transfers))
> + m_param = FRAGMENTATION;
> + }
> +
> + mas->cur_xfer = xfer;
> + if (m_cmd & SPI_TX_ONLY) {
> + mas->tx_rem_bytes = xfer->len;
> + writel(trans_len, se->base + SE_SPI_TX_TRANS_LEN);
> + }
> +
> + if (m_cmd & SPI_RX_ONLY) {
> + writel(trans_len, se->base + SE_SPI_RX_TRANS_LEN);
> + mas->rx_rem_bytes = xfer->len;
> + }
> + writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);
> + geni_se_setup_m_cmd(se, m_cmd, m_param);
> +
> + /*
> + * TX_WATERMARK_REG should be set after SPI configuration and
> + * setting up GENI SE engine, as driver starts data transfer
> + * for the watermark interrupt.
> + */
> + if (m_cmd & SPI_TX_ONLY)
> + writel(mas->tx_wm, se->base + SE_GENI_TX_WATERMARK_REG);
> +}
> +
> +static void handle_fifo_timeout(struct spi_master *spi,
> + struct spi_message *msg)
> +{
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> + unsigned long timeout, flags;
> + struct geni_se *se = &mas->se;
> +
> + spin_lock_irqsave(&mas->lock, flags);
> + reinit_completion(&mas->xfer_done);
> + geni_se_cancel_m_cmd(se);
> + writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
> + spin_unlock_irqrestore(&mas->lock, flags);
> + timeout = wait_for_completion_timeout(&mas->xfer_done, HZ);

Can you rename this time_left or completed? Then the if condition reads
properly as "if not time left" or "if not completed". And then invert
that logic so things aren't so indented?

time_left = wait_for_completion_timeout(..)
if (time_left)
return;

spin_lock_irqsave(&mas->lock, flags);
reinit_completion(..)
...

> + if (!timeout) {
> + spin_lock_irqsave(&mas->lock, flags);
> + reinit_completion(&mas->xfer_done);
> + geni_se_abort_m_cmd(se);
> + spin_unlock_irqrestore(&mas->lock, flags);
> + timeout = wait_for_completion_timeout(&mas->xfer_done,
> + HZ);
> + if (!timeout)
> + dev_err(mas->dev,
> + "Failed to cancel/abort m_cmd\n");
> + }
> +}
> +
> +static int spi_geni_transfer_one(struct spi_master *spi,
> + struct spi_device *slv,
> + struct spi_transfer *xfer)
> +{
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> +
> + setup_fifo_xfer(xfer, mas, slv->mode, spi);
> + return 1;
> +}
> +
> +static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
> +{
> + /*
> + * Calculate how many bytes we'll put in each FIFO word. If the
> + * transfer words don't pack cleanly into a FIFO word we'll just put
> + * one transfer word in each FIFO word. If they do pack we'll pack 'em.
> + */
> + if (mas->fifo_width_bits % mas->cur_bits_per_word)
> + return roundup_pow_of_two(DIV_ROUND_UP(mas->cur_bits_per_word,
> + BITS_PER_BYTE));
> + else
> + return mas->fifo_width_bits / BITS_PER_BYTE;

Just do a return. No else please.

> +}
> +
> +static irqreturn_t geni_spi_handle_tx(struct spi_geni_master *mas)
> +{
> + struct geni_se *se = &mas->se;
> + unsigned int max_bytes;
> + const u8 *tx_buf;
> + unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
> + unsigned int i = 0;
> +
> + if (!mas->cur_xfer)
> + return IRQ_NONE;
> +
> + max_bytes = (mas->tx_fifo_depth - mas->tx_wm) * bytes_per_fifo_word;
> + if (mas->tx_rem_bytes < max_bytes)
> + max_bytes = mas->tx_rem_bytes;
> +
> + tx_buf = mas->cur_xfer->tx_buf + mas->cur_xfer->len - mas->tx_rem_bytes;
> + while (i < max_bytes) {
> + unsigned int j;
> + unsigned int bytes_to_write;
> + u32 fifo_word = 0;
> + u8 *fifo_byte = (u8 *)&fifo_word;
> +
> + bytes_to_write = min(bytes_per_fifo_word, max_bytes - i);
> + for (j = 0; j < bytes_to_write; j++)
> + fifo_byte[j] = tx_buf[i++];
> + iowrite32_rep(se->base + SE_GENI_TX_FIFOn, &fifo_word, 1);
> + }
> + mas->tx_rem_bytes -= max_bytes;
> + if (!mas->tx_rem_bytes)
> + writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t geni_spi_handle_rx(struct spi_geni_master *mas)
> +{
> + struct geni_se *se = &mas->se;
> + u32 rx_fifo_status;
> + unsigned int rx_bytes;
> + u8 *rx_buf;
> + unsigned int bytes_per_fifo_word = geni_byte_per_fifo_word(mas);
> + unsigned int i = 0;
> +
> + if (!mas->cur_xfer)
> + return IRQ_NONE;
> +
> + rx_fifo_status = readl(se->base + SE_GENI_RX_FIFO_STATUS);

Rename to 'status'? rx_fifo is implicit in the register macro.

> + rx_bytes = (rx_fifo_status & RX_FIFO_WC_MSK) * bytes_per_fifo_word;
> + if (rx_fifo_status & RX_LAST) {
> + unsigned int rx_last_byte_valid =
> + (rx_fifo_status & RX_LAST_BYTE_VALID_MSK)
> + >> RX_LAST_BYTE_VALID_SHFT;

Hoist this variable into function scope? So then the line is:

last_valid = status & RX_LAST_BYTE_VALID_MSK;
last_valid >>= RX_LAST_BYTE_VALID_SHFT;

> + if (rx_last_byte_valid && (rx_last_byte_valid < 4))

Drop useless parenthesis please.

> + rx_bytes -= bytes_per_fifo_word - rx_last_byte_valid;
> + }
> + if (mas->rx_rem_bytes < rx_bytes)
> + rx_bytes = mas->rx_rem_bytes;
> +
> + rx_buf = mas->cur_xfer->rx_buf + mas->cur_xfer->len - mas->rx_rem_bytes;
> + while (i < rx_bytes) {
> + u32 fifo_word = 0;
> + u8 *fifo_byte = (u8 *)&fifo_word;
> + unsigned int bytes_to_read;
> + unsigned int j;
> +
> + bytes_to_read = min(bytes_per_fifo_word, rx_bytes - i);
> + ioread32_rep(se->base + SE_GENI_RX_FIFOn, &fifo_word, 1);
> + for (j = 0; j < bytes_to_read; j++)
> + rx_buf[i++] = fifo_byte[j];
> + }
> + mas->rx_rem_bytes -= rx_bytes;
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t geni_spi_isr(int irq, void *data)
> +{
> + struct spi_master *spi = data;
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> + struct geni_se *se = &mas->se;
> + u32 m_irq;
> + unsigned long flags;
> + irqreturn_t ret = IRQ_HANDLED;
> +
> + if (pm_runtime_status_suspended(mas->dev))
> + return IRQ_NONE;
> +
> + spin_lock_irqsave(&mas->lock, flags);
> + m_irq = readl(se->base + SE_GENI_M_IRQ_STATUS);
> + if ((m_irq & M_RX_FIFO_WATERMARK_EN) || (m_irq & M_RX_FIFO_LAST_EN))
> + ret = geni_spi_handle_rx(mas);
> +
> + if (m_irq & M_TX_FIFO_WATERMARK_EN)
> + ret = geni_spi_handle_tx(mas);

Is it possible for all three conditions above to happen in one
interrupt? I ask because 'ret' is overwritten and so what may have been
IRQ_HANDLED may become IRQ_NONE which will lead to confusion in the irq
layer. Maybe the handle tx/rx functions can return a bool, that gets
orred together each time so that we know if something handled an
interrupt?

> +
> + if (m_irq & M_CMD_DONE_EN) {
> + spi_finalize_current_transfer(spi);
> + /*
> + * If this happens, then a CMD_DONE came before all the Tx
> + * buffer bytes were sent out. This is unusual, log this
> + * condition and disable the WM interrupt to prevent the
> + * system from stalling due an interrupt storm.
> + * If this happens when all Rx bytes haven't been received, log
> + * the condition.
> + * The only known time this can happen is if bits_per_word != 8
> + * and some registers that expect xfer lengths in num spi_words
> + * weren't written correctly.
> + */
> + if (mas->tx_rem_bytes) {
> + writel(0, se->base + SE_GENI_TX_WATERMARK_REG);
> + dev_err(mas->dev, "Premature Done.tx_rem%d bpw%d\n",

Why isn't there a space after "Done."? And why is 'done' capitalized?
Should 'tx_rem' be 'tx_rem='?

> + mas->tx_rem_bytes, mas->cur_bits_per_word);
> + }
> + if (mas->rx_rem_bytes)
> + dev_err(mas->dev, "Premature Done.rx_rem%d bpw%d\n",
> + mas->rx_rem_bytes, mas->cur_bits_per_word);
> + }
> +
> + if ((m_irq & M_CMD_CANCEL_EN) || (m_irq & M_CMD_ABORT_EN))
> + complete(&mas->xfer_done);
> +
> + writel(m_irq, se->base + SE_GENI_M_IRQ_CLEAR);
> + spin_unlock_irqrestore(&mas->lock, flags);
> + return ret;
> +}
> +
> +static int spi_geni_probe(struct platform_device *pdev)
> +{
> + int ret;
> + struct spi_master *spi;
> + struct spi_geni_master *mas;
> + struct resource *res;
> + struct geni_se *se;
> +
> + spi = spi_alloc_master(&pdev->dev, sizeof(struct spi_geni_master));

sizeof(*mas) for code clarity?

> + if (!spi)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, spi);
> + mas = spi_master_get_devdata(spi);
> + mas->dev = &pdev->dev;
> + mas->se.dev = &pdev->dev;
> + mas->se.wrapper = dev_get_drvdata(pdev->dev.parent);
> + se = &mas->se;
> +
> + spi->bus_num = -1;
> + spi->dev.of_node = pdev->dev.of_node;
> + mas->se.clk = devm_clk_get(&pdev->dev, "se");
> + if (IS_ERR(mas->se.clk)) {
> + ret = PTR_ERR(mas->se.clk);
> + dev_err(&pdev->dev, "Err getting SE Core clk %d\n", ret);
> + goto spi_geni_probe_err;
> + }
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + se->base = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(se->base)) {
> + ret = -ENOMEM;

ret = PTR_ERR(se->base);

so we don't lose the error value.

> + goto spi_geni_probe_err;
> + }
> +
> + ret = platform_get_irq(pdev, 0);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "Err getting IRQ %d\n", ret);
> + goto spi_geni_probe_err;
> + }
> + ret = devm_request_irq(&pdev->dev, ret, geni_spi_isr,
> + IRQF_TRIGGER_HIGH, "spi_geni", spi);
> + if (ret)
> + goto spi_geni_probe_err;

Can you request this irq as late as possible in the probe function? I
worry there may be some pending irq line set and then this will cause an
interrupt storm with IRQ_NONE returned because the device is runtime
suspended.

> +
> + spi->mode_bits = SPI_CPOL | SPI_CPHA | SPI_LOOP | SPI_CS_HIGH;
> + spi->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
> + spi->num_chipselect = 4;
> + spi->max_speed_hz = 50000000;
> + spi->prepare_message = spi_geni_prepare_message;
> + spi->transfer_one = spi_geni_transfer_one;
> + spi->auto_runtime_pm = true;
> + spi->handle_err = handle_fifo_timeout;
> +
> + init_completion(&mas->xfer_done);
> + spin_lock_init(&mas->lock);
> + pm_runtime_enable(&pdev->dev);
> +
> + ret = spi_geni_init(mas);
> + if (ret)
> + goto spi_geni_probe_runtime_disable;
> +
> + ret = spi_register_master(spi);
> + if (ret)
> + goto spi_geni_probe_runtime_disable;
> +
> + return 0;
> +spi_geni_probe_runtime_disable:
> + pm_runtime_disable(&pdev->dev);
> +spi_geni_probe_err:
> + spi_master_put(spi);
> + return ret;
> +}
> +
> +static int spi_geni_remove(struct platform_device *pdev)
> +{
> + struct spi_master *spi = platform_get_drvdata(pdev);
> +
> + /* Unregister _before_ disabling pm_runtime() so we stop transfers */
> + spi_unregister_master(spi);
> +
> + pm_runtime_disable(&pdev->dev);
> + return 0;
> +}
> +
> +static int __maybe_unused spi_geni_runtime_suspend(struct device *dev)
> +{
> + struct spi_master *spi = dev_get_drvdata(dev);
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> +
> + return geni_se_resources_off(&mas->se);
> +}
> +
> +static int __maybe_unused spi_geni_runtime_resume(struct device *dev)
> +{
> + struct spi_master *spi = dev_get_drvdata(dev);
> + struct spi_geni_master *mas = spi_master_get_devdata(spi);
> +
> + return geni_se_resources_on(&mas->se);
> +}
> +
> +static int __maybe_unused spi_geni_suspend(struct device *dev)
> +{
> + if (!pm_runtime_status_suspended(dev))
> + return -EBUSY;
> + return 0;
> +}
> +
> +static const struct dev_pm_ops spi_geni_pm_ops = {
> + SET_RUNTIME_PM_OPS(spi_geni_runtime_suspend,
> + spi_geni_runtime_resume, NULL)
> + SET_SYSTEM_SLEEP_PM_OPS(spi_geni_suspend, NULL)
> +};
> +
> +static const struct of_device_id spi_geni_dt_match[] = {
> + { .compatible = "qcom,geni-spi" },
> + {}
> +};

Please add a MODULE_DEVICE_TABLE(of, spi_geni_dt_match) here.

> +
> +static struct platform_driver spi_geni_driver = {
> + .probe = spi_geni_probe,
> + .remove = spi_geni_remove,
> + .driver = {
> + .name = "geni_spi",
> + .pm = &spi_geni_pm_ops,
> + .of_match_table = spi_geni_dt_match,
> + },
> +};
> +module_platform_driver(spi_geni_driver);
> +
> +MODULE_DESCRIPTION("SPI driver for GENI based QUP cores");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/spi/spi-geni-qcom.h b/include/linux/spi/spi-geni-qcom.h
> new file mode 100644
> index 0000000..dc95764
> --- /dev/null
> +++ b/include/linux/spi/spi-geni-qcom.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Copyright (c) 2017-2018, The Linux Foundation. All rights reserved.
> + */
> +
> +#ifndef __SPI_GENI_QCOM_HEADER___
> +#define __SPI_GENI_QCOM_HEADER___
> +
> +struct spi_geni_qcom_ctrl_data {
> + u32 spi_cs_clk_delay;
> + u32 spi_inter_words_delay;
It was decided we still needed this? I don't see it in v3 so please
remove this file unless it's needed.

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