Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760880Ab3JPWCM (ORCPT ); Wed, 16 Oct 2013 18:02:12 -0400 Received: from mms2.broadcom.com ([216.31.210.18]:2628 "EHLO mms2.broadcom.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752419Ab3JPWCI (ORCPT ); Wed, 16 Oct 2013 18:02:08 -0400 X-Server-Uuid: 4500596E-606A-40F9-852D-14843D8201B2 From: "Tim Kryger" To: "Christian Daudt" , "Rob Herring" , "Pawel Moll" , "Mark Rutland" , "Stephen Warren" , "Ian Campbell" , "Rob Landley" , "Wolfram Sang" , "Grant Likely" cc: "Tim Kryger" , devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-i2c@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: [RESEND PATCH 2/4] i2c: i2c-bcm-kona: Add support for high-speed mode Date: Wed, 16 Oct 2013 15:01:47 -0700 Message-ID: <1381960909-1735-3-git-send-email-tim.kryger@linaro.org> X-Mailer: git-send-email 1.8.0.1 In-Reply-To: <1381960909-1735-1-git-send-email-tim.kryger@linaro.org> References: <1381960909-1735-1-git-send-email-tim.kryger@linaro.org> MIME-Version: 1.0 X-WSS-ID: 7E41D35A1R0101266432-01-01 Content-Type: text/plain Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6134 Lines: 207 Add support for I2C high-speed mode (3.4 MHz). Signed-off-by: Tim Kryger Reviewed-by: Matt Porter Reviewed-by: Markus Mayer --- drivers/i2c/busses/i2c-bcm-kona.c | 116 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) diff --git a/drivers/i2c/busses/i2c-bcm-kona.c b/drivers/i2c/busses/i2c-bcm-kona.c index 2936acf..458714f 100644 --- a/drivers/i2c/busses/i2c-bcm-kona.c +++ b/drivers/i2c/busses/i2c-bcm-kona.c @@ -77,6 +77,9 @@ #define HSTIM_OFFSET 0x00000058 #define HSTIM_HS_MODE_MASK 0x00008000 +#define HSTIM_HS_HOLD_SHIFT 10 +#define HSTIM_HS_HIGH_PHASE_SHIFT 5 +#define HSTIM_HS_SETUP_SHIFT 0 #define PADCTL_OFFSET 0x0000005c #define PADCTL_PAD_OUT_EN_MASK 0x00000004 @@ -91,6 +94,9 @@ #define MAX_TX_FIFO_SIZE 64U /* bytes */ #define STD_EXT_CLK_FREQ 13000000UL +#define HS_EXT_CLK_FREQ 104000000UL + +#define MASTERCODE 0x08 /* Mastercodes are 0000_1xxxb */ #define I2C_TIMEOUT 100 /* msecs */ @@ -108,6 +114,10 @@ enum bus_speed_index { BCM_SPD_1MHZ, }; +enum hs_bus_speed_index { + BCM_SPD_3P4MHZ = 0, +}; + /* Internal divider settings for standard mode, fast mode and fast mode plus */ struct bus_speed_cfg { uint8_t time_m; /* Number of cycles for setup time */ @@ -118,12 +128,30 @@ struct bus_speed_cfg { uint8_t time_div; /* Post-prescale divider */ }; +/* Internal divider settings for high-speed mode */ +struct hs_bus_speed_cfg { + uint8_t hs_hold; /* Number of clock cycles SCL stays low until + the end of bit period */ + uint8_t hs_high_phase; /* Number of clock cycles SCL stays high + before it falls */ + uint8_t hs_setup; /* Number of clock cycles SCL stays low + before it rises */ + uint8_t prescale; /* Prescale divider */ + uint8_t time_p; /* Timing coefficient */ + uint8_t no_div; /* Disable clock divider */ + uint8_t time_div; /* Post-prescale divider */ +}; + static const struct bus_speed_cfg std_cfg_table[] = { [BCM_SPD_100K] = {0x01, 0x01, 0x03, 0x06, 0x00, 0x02}, [BCM_SPD_400K] = {0x05, 0x01, 0x03, 0x05, 0x01, 0x02}, [BCM_SPD_1MHZ] = {0x01, 0x01, 0x03, 0x01, 0x01, 0x03}, }; +static const struct hs_bus_speed_cfg hs_cfg_table[] = { + [BCM_SPD_3P4MHZ] = {0x01, 0x08, 0x14, 0x00, 0x06, 0x01, 0x00}, +}; + struct bcm_kona_i2c_dev { /* Pointer to linux device struct */ struct device *device; @@ -137,6 +165,9 @@ struct bcm_kona_i2c_dev { /* Standard Speed configuration */ const struct bus_speed_cfg *std_cfg; + /* High Speed configuration (if applicable) */ + const struct hs_bus_speed_cfg *hs_cfg; + /* Linux I2C adapter struct */ struct i2c_adapter adapter; @@ -520,6 +551,72 @@ static void bcm_kona_i2c_config_timing(struct bcm_kona_i2c_dev *dev) dev->base + CLKEN_OFFSET); } +static void bcm_kona_i2c_config_timing_hs(struct bcm_kona_i2c_dev *dev) +{ + writel((dev->hs_cfg->prescale << TIM_PRESCALE_SHIFT) | + (dev->hs_cfg->time_p << TIM_P_SHIFT) | + (dev->hs_cfg->no_div << TIM_NO_DIV_SHIFT) | + (dev->hs_cfg->time_div << TIM_DIV_SHIFT), + dev->base + TIM_OFFSET); + + writel((dev->hs_cfg->hs_hold << HSTIM_HS_HOLD_SHIFT) | + (dev->hs_cfg->hs_high_phase << HSTIM_HS_HIGH_PHASE_SHIFT) | + (dev->hs_cfg->hs_setup << HSTIM_HS_SETUP_SHIFT), + dev->base + HSTIM_OFFSET); + + writel(readl(dev->base + HSTIM_OFFSET) | HSTIM_HS_MODE_MASK, + dev->base + HSTIM_OFFSET); +} + +static int bcm_kona_i2c_switch_to_hs(struct bcm_kona_i2c_dev *dev) +{ + int rc; + + /* Send mastercode at standard speed */ + rc = bcm_kona_i2c_write_byte(dev, MASTERCODE, 1); + if (rc < 0) { + pr_err("High speed handshake failed\n"); + return rc; + } + + /* Configure external clock to higher frequency */ + rc = clk_set_rate(dev->external_clk, HS_EXT_CLK_FREQ); + if (rc) { + dev_err(dev->device, "%s: clk_set_rate returned %d\n", + __func__, rc); + return rc; + } + + /* Reconfigure internal dividers */ + bcm_kona_i2c_config_timing_hs(dev); + + /* Send a restart command */ + rc = bcm_kona_send_i2c_cmd(dev, BCM_CMD_RESTART); + if (rc < 0) { + dev_err(dev->device, + "High speed restart command failed rc = %d\n", rc); + } + + return rc; +} + +static int bcm_kona_i2c_switch_to_std(struct bcm_kona_i2c_dev *dev) +{ + int rc; + + /* Reconfigure internal dividers */ + bcm_kona_i2c_config_timing(dev); + + /* Configure external clock to lower frequency */ + rc = clk_set_rate(dev->external_clk, STD_EXT_CLK_FREQ); + if (rc) { + dev_err(dev->device, "%s: clk_set_rate returned %d\n", + __func__, rc); + } + + return rc; +} + /* Master transfer function */ static int bcm_kona_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg msgs[], int num) @@ -551,6 +648,13 @@ static int bcm_kona_i2c_xfer(struct i2c_adapter *adapter, goto xfer_disable_pad; } + /* Switch to high speed if applicable */ + if (dev->hs_cfg) { + rc = bcm_kona_i2c_switch_to_hs(dev); + if (rc < 0) + goto xfer_send_stop; + } + /* Loop through all messages */ for (i = 0; i < num; i++) { pmsg = &msgs[i]; @@ -598,6 +702,13 @@ xfer_send_stop: /* Send a STOP command */ bcm_kona_send_i2c_cmd(dev, BCM_CMD_STOP); + /* Return from high speed if applicable */ + if (dev->hs_cfg) { + int hs_rc = bcm_kona_i2c_switch_to_std(dev); + if (hs_rc) + rc = hs_rc; + } + xfer_disable_pad: /* Disable pad output */ writel(PADCTL_PAD_OUT_EN_MASK, dev->base + PADCTL_OFFSET); @@ -642,6 +753,11 @@ static int bcm_kona_i2c_assign_bus_speed(struct bcm_kona_i2c_dev *dev) case 1000000: dev->std_cfg = &std_cfg_table[BCM_SPD_1MHZ]; break; + case 3400000: + /* Send mastercode at 100k */ + dev->std_cfg = &std_cfg_table[BCM_SPD_100K]; + dev->hs_cfg = &hs_cfg_table[BCM_SPD_3P4MHZ]; + break; default: pr_err("%d hz bus speed not supported\n", bus_speed); return -EINVAL; -- 1.8.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/